AL4 postcode district: St Albans and around, Hertfordshire

AL4 is a postcode district in Hertfordshire, with 787 postcodes in use in 3 sectors. It has postcodes in St Albans, Wheathampstead, Hatfield and 1 more place. It is split between 4 councils: St Albans (762 postcodes), North Hertfordshire (12), Welwyn Hatfield (10) and 1 other.

Postcodes in use
787
Sectors
3
Councils
4 councils
Places
4 places

Source: Office for National Statistics (ONS) Postcode Directory, August 2026, loaded 20 October 2026. See all our data sources

Every postcode in AL4, by flood risk

Map of every postcode in AL4, by flood risk Of the 787 postcodes in AL4 that ONS places, 13 have a home or business at high risk, 1 are at medium risk at worst, 9 are at low risk at worst, 1 are at very low risk only and 763 are not on the Environment Agency's at-risk list. One group of postcodes at high or medium risk is outlined: 5 postcodes at high or medium risk. Places named: St Albans, Harpenden, Hatfield, Welwyn, Wheathampstead, Welham Green. Drawn over roads, rivers and built-up areas. North is up; the scale bar is 2 km. A1081A5183A1(M)A1000 AL4 0AA: not on the flood risk listAL4 0AB: not on the flood risk listAL4 0AD: not on the flood risk listAL4 0AE: not on the flood risk listAL4 0AG: not on the flood risk listAL4 0AH: not on the flood risk listAL4 0AJ: not on the flood risk listAL4 0AN: not on the flood risk listAL4 0AT: not on the flood risk listAL4 0AW: not on the flood risk listAL4 0AY: not on the flood risk listAL4 0BA: not on the flood risk listAL4 0BB: not on the flood risk listAL4 0BD: not on the flood risk listAL4 0BF: not on the flood risk listAL4 0BG: not on the flood risk listAL4 0BJ: not on the flood risk listAL4 0BN: not on the flood risk listAL4 0BP: not on the flood risk listAL4 0BQ: not on the flood risk listAL4 0BS: not on the flood risk listAL4 0BT: not on the flood risk listAL4 0BU: not on the flood risk listAL4 0BW: not on the flood risk listAL4 0BX: not on the flood risk listAL4 0BY: not on the flood risk listAL4 0DB: not on the flood risk listAL4 0DE: not on the flood risk listAL4 0DF: not on the flood risk listAL4 0DG: not on the flood risk listAL4 0DH: not on the flood risk listAL4 0DJ: not on the flood risk listAL4 0DL: not on the flood risk listAL4 0DN: not on the flood risk listAL4 0DP: not on the flood risk listAL4 0DQ: not on the flood risk listAL4 0DR: not on the flood risk listAL4 0DS: not on the flood risk listAL4 0DW: not on the flood risk listAL4 0DY: not on the flood risk listAL4 0EB: not on the flood risk listAL4 0EE: not on the flood risk listAL4 0EG: not on the flood risk listAL4 0EH: not on the flood risk listAL4 0EL: not on the flood risk listAL4 0EN: not on the flood risk listAL4 0EP: not on the flood risk listAL4 0EQ: not on the flood risk listAL4 0ES: not on the flood risk listAL4 0EW: not on the flood risk listAL4 0EX: not on the flood risk listAL4 0EZ: not on the flood risk listAL4 0FE: not on the flood risk listAL4 0FH: not on the flood risk listAL4 0FJ: not on the flood risk listAL4 0FN: not on the flood risk listAL4 0FQ: not on the flood risk listAL4 0FR: not on the flood risk listAL4 0FS: not on the flood risk listAL4 0FT: not on the flood risk listAL4 0FU: not on the flood risk listAL4 0FW: not on the flood risk listAL4 0FX: not on the flood risk listAL4 0FZ: not on the flood risk listAL4 0GB: not on the flood risk listAL4 0GD: not on the flood risk listAL4 0GF: not on the flood risk listAL4 0GL: not on the flood risk listAL4 0GN: not on the flood risk listAL4 0GQ: not on the flood risk listAL4 0GS: not on the flood risk listAL4 0GT: not on the flood risk listAL4 0GY: not on the flood risk listAL4 0HA: not on the flood risk listAL4 0HB: not on the flood risk listAL4 0HD: not on the flood risk listAL4 0HE: not on the flood risk listAL4 0HF: not on the flood risk listAL4 0HG: not on the flood risk listAL4 0HH: not on the flood risk listAL4 0HJ: not on the flood risk listAL4 0HL: not on the flood risk listAL4 0HN: not on the flood risk listAL4 0HP: not on the flood risk listAL4 0HQ: not on the flood risk listAL4 0HR: not on the flood risk listAL4 0HS: not on the flood risk listAL4 0HT: not on the flood risk listAL4 0HU: not on the flood risk listAL4 0HW: not on the flood risk listAL4 0HX: not on the flood risk listAL4 0HY: not on the flood risk listAL4 0HZ: not on the flood risk listAL4 0JA: not on the flood risk listAL4 0JB: not on the flood risk listAL4 0JE: not on the flood risk listAL4 0JG: not on the flood risk listAL4 0JJ: not on the flood risk listAL4 0JP: not on the flood risk listAL4 0JR: not on the flood risk listAL4 0JS: not on the flood risk listAL4 0JY: not on the flood risk listAL4 0JZ: not on the flood risk listAL4 0LA: not on the flood risk listAL4 0LB: not on the flood risk listAL4 0LD: not on the flood risk listAL4 0LE: not on the flood risk listAL4 0LG: not on the flood risk listAL4 0LH: not on the flood risk listAL4 0LJ: not on the flood risk listAL4 0LP: not on the flood risk listAL4 0LQ: not on the flood risk listAL4 0LT: not on the flood risk listAL4 0LW: not on the flood risk listAL4 0LY: not on the flood risk listAL4 0ND: not on the flood risk listAL4 0NE: not on the flood risk listAL4 0NF: not on the flood risk listAL4 0NG: not on the flood risk listAL4 0NH: not on the flood risk listAL4 0NL: not on the flood risk listAL4 0NN: not on the flood risk listAL4 0NP: not on the flood risk listAL4 0NT: not on the flood risk listAL4 0NW: not on the flood risk listAL4 0NX: not on the flood risk listAL4 0NY: not on the flood risk listAL4 0NZ: not on the flood risk listAL4 0PD: not on the flood risk listAL4 0PJ: not on the flood risk listAL4 0PL: not on the flood risk listAL4 0PP: not on the flood risk listAL4 0PQ: not on the flood risk listAL4 0PR: not on the flood risk listAL4 0PS: not on the flood risk listAL4 0PT: not on the flood risk listAL4 0PU: not on the flood risk listAL4 0PW: not on the flood risk listAL4 0PX: not on the flood risk listAL4 0PZ: not on the flood risk listAL4 0QA: not on the flood risk listAL4 0QD: not on the flood risk listAL4 0QH: not on the flood risk listAL4 0QJ: not on the flood risk listAL4 0QL: not on the flood risk listAL4 0QN: not on the flood risk listAL4 0QQ: not on the flood risk listAL4 0QR: not on the flood risk listAL4 0QS: not on the flood risk listAL4 0QT: not on the flood risk listAL4 0QU: not on the flood risk listAL4 0QW: not on the flood risk listAL4 0RA: not on the flood risk listAL4 0RE: not on the flood risk listAL4 0RH: not on the flood risk listAL4 0RJ: not on the flood risk listAL4 0RN: not on the flood risk listAL4 0RP: not on the flood risk listAL4 0RQ: not on the flood risk listAL4 0RR: not on the flood risk listAL4 0RS: not on the flood risk listAL4 0RW: not on the flood risk listAL4 0RX: not on the flood risk listAL4 0RZ: not on the flood risk listAL4 0SA: not on the flood risk listAL4 0SB: not on the flood risk listAL4 0SD: not on the flood risk listAL4 0SF: not on the flood risk listAL4 0SH: not on the flood risk listAL4 0SL: not on the flood risk listAL4 0SN: not on the flood risk listAL4 0SP: not on the flood risk listAL4 0ST: not on the flood risk listAL4 0SW: not on the flood risk listAL4 0SX: not on the flood risk listAL4 0SY: not on the flood risk listAL4 0SZ: not on the flood risk listAL4 0TA: not on the flood risk listAL4 0TB: not on the flood risk listAL4 0TD: not on the flood risk listAL4 0TG: not on the flood risk listAL4 0TH: not on the flood risk listAL4 0TJ: not on the flood risk listAL4 0TN: not on the flood risk listAL4 0TP: not on the flood risk listAL4 0TQ: not on the flood risk listAL4 0TT: not on the flood risk listAL4 0TU: not on the flood risk listAL4 0TX: not on the flood risk listAL4 0TZ: not on the flood risk listAL4 0UA: not on the flood risk listAL4 0UB: not on the flood risk listAL4 0UD: not on the flood risk listAL4 0UE: not on the flood risk listAL4 0UH: not on the flood risk listAL4 0UL: not on the flood risk listAL4 0UN: not on the flood risk listAL4 0UP: not on the flood risk listAL4 0UQ: not on the flood risk listAL4 0UR: not on the flood risk listAL4 0UX: not on the flood risk listAL4 0UY: not on the flood risk listAL4 0WA: not on the flood risk listAL4 0XA: not on the flood risk listAL4 0XB: not on the flood risk listAL4 0XD: not on the flood risk listAL4 0XE: not on the flood risk listAL4 0XH: not on the flood risk listAL4 0XL: not on the flood risk listAL4 0XP: not on the flood risk listAL4 0XR: not on the flood risk listAL4 0XX: not on the flood risk listAL4 0XZ: not on the flood risk listAL4 8AD: not on the flood risk listAL4 8AE: not on the flood risk listAL4 8AG: not on the flood risk listAL4 8AH: not on the flood risk listAL4 8AJ: not on the flood risk listAL4 8AN: not on the flood risk listAL4 8AP: not on the flood risk listAL4 8AQ: not on the flood risk listAL4 8AR: not on the flood risk listAL4 8AS: not on the flood risk listAL4 8AT: not on the flood risk listAL4 8AX: not on the flood risk listAL4 8AY: not on the flood risk listAL4 8BA: not on the flood risk listAL4 8BD: not on the flood risk listAL4 8BE: not on the flood risk listAL4 8BH: not on the flood risk listAL4 8BN: not on the flood risk listAL4 8BT: not on the flood risk listAL4 8BW: not on the flood risk listAL4 8BX: not on the flood risk listAL4 8DB: not on the flood risk listAL4 8DD: not on the flood risk listAL4 8DJ: not on the flood risk listAL4 8DX: not on the flood risk listAL4 8DY: not on the flood risk listAL4 8DZ: not on the flood risk listAL4 8EA: not on the flood risk listAL4 8EB: not on the flood risk listAL4 8ED: not on the flood risk listAL4 8EE: not on the flood risk listAL4 8EG: not on the flood risk listAL4 8EJ: not on the flood risk listAL4 8EL: not on the flood risk listAL4 8EN: not on the flood risk listAL4 8EP: not on the flood risk listAL4 8EQ: not on the flood risk listAL4 8ER: not on the flood risk listAL4 8ES: not on the flood risk listAL4 8ET: not on the flood risk listAL4 8EU: not on the flood risk listAL4 8EW: not on the flood risk listAL4 8EX: not on the flood risk listAL4 8EY: not on the flood risk listAL4 8EZ: not on the flood risk listAL4 8FB: not on the flood risk listAL4 8FD: not on the flood risk listAL4 8FE: not on the flood risk listAL4 8FH: not on the flood risk listAL4 8GB: not on the flood risk listAL4 8HA: not on the flood risk listAL4 8HD: not on the flood risk listAL4 8HE: not on the flood risk listAL4 8HJ: not on the flood risk listAL4 8HN: not on the flood risk listAL4 8HP: not on the flood risk listAL4 8HR: not on the flood risk listAL4 8HS: not on the flood risk listAL4 8HT: not on the flood risk listAL4 8HU: not on the flood risk listAL4 8HX: not on the flood risk listAL4 8HY: not on the flood risk listAL4 8JA: not on the flood risk listAL4 8JB: not on the flood risk listAL4 8JD: not on the flood risk listAL4 8JE: not on the flood risk listAL4 8JF: not on the flood risk listAL4 8JG: not on the flood risk listAL4 8JH: not on the flood risk listAL4 8JN: not on the flood risk listAL4 8JQ: not on the flood risk listAL4 8LA: not on the flood risk listAL4 8LB: not on the flood risk listAL4 8LD: not on the flood risk listAL4 8LE: not on the flood risk listAL4 8LG: not on the flood risk listAL4 8LH: not on the flood risk listAL4 8LJ: not on the flood risk listAL4 8LL: not on the flood risk listAL4 8LN: not on the flood risk listAL4 8LP: not on the flood risk listAL4 8LQ: not on the flood risk listAL4 8LR: not on the flood risk listAL4 8LS: not on the flood risk listAL4 8LT: not on the flood risk listAL4 8LU: not on the flood risk listAL4 8LW: not on the flood risk listAL4 8LX: not on the flood risk listAL4 8LY: not on the flood risk listAL4 8LZ: not on the flood risk listAL4 8ND: not on the flood risk listAL4 8NH: not on the flood risk listAL4 8NN: not on the flood risk listAL4 8NP: not on the flood risk listAL4 8NQ: not on the flood risk listAL4 8NR: not on the flood risk listAL4 8NS: not on the flood risk listAL4 8NT: not on the flood risk listAL4 8NU: not on the flood risk listAL4 8NW: not on the flood risk listAL4 8NY: not on the flood risk listAL4 8NZ: not on the flood risk listAL4 8PB: not on the flood risk listAL4 8PD: not on the flood risk listAL4 8PE: not on the flood risk listAL4 8PG: not on the flood risk listAL4 8PP: not on the flood risk listAL4 8PR: not on the flood risk listAL4 8PS: not on the flood risk listAL4 8PU: not on the flood risk listAL4 8PX: not on the flood risk listAL4 8PZ: not on the flood risk listAL4 8QB: not on the flood risk listAL4 8QE: not on the flood risk listAL4 8QF: not on the flood risk listAL4 8QH: not on the flood risk listAL4 8QJ: not on the flood risk listAL4 8QZ: not on the flood risk listAL4 8RA: not on the flood risk listAL4 8RB: not on the flood risk listAL4 8RD: not on the flood risk listAL4 8RG: not on the flood risk listAL4 8RH: not on the flood risk listAL4 8RJ: not on the flood risk listAL4 8RL: not on the flood risk listAL4 8RN: not on the flood risk listAL4 8RP: not on the flood risk listAL4 8RQ: not on the flood risk listAL4 8RR: not on the flood risk listAL4 8RS: not on the flood risk listAL4 8RT: not on the flood risk listAL4 8RU: not on the flood risk listAL4 8RW: not on the flood risk listAL4 8RX: not on the flood risk listAL4 8SA: not on the flood risk listAL4 8TA: not on the flood risk listAL4 8TB: not on the flood risk listAL4 8TD: not on the flood risk listAL4 8TE: not on the flood risk listAL4 8TH: not on the flood risk listAL4 8TJ: not on the flood risk listAL4 8TL: not on the flood risk listAL4 8TN: not on the flood risk listAL4 8TQ: not on the flood risk listAL4 8TS: not on the flood risk listAL4 8TT: not on the flood risk listAL4 9AA: not on the flood risk listAL4 9AB: not on the flood risk listAL4 9AD: not on the flood risk listAL4 9AE: not on the flood risk listAL4 9AH: not on the flood risk listAL4 9AJ: not on the flood risk listAL4 9AL: not on the flood risk listAL4 9AN: not on the flood risk listAL4 9AP: not on the flood risk listAL4 9AQ: not on the flood risk listAL4 9AS: not on the flood risk listAL4 9AT: not on the flood risk listAL4 9AU: not on the flood risk listAL4 9AW: not on the flood risk listAL4 9AX: not on the flood risk listAL4 9AZ: not on the flood risk listAL4 9BA: not on the flood risk listAL4 9BD: not on the flood risk listAL4 9BG: not on the flood risk listAL4 9BH: not on the flood risk listAL4 9BL: not on the flood risk listAL4 9BQ: not on the flood risk listAL4 9BS: not on the flood risk listAL4 9BU: not on the flood risk listAL4 9BX: not on the flood risk listAL4 9BY: not on the flood risk listAL4 9DA: not on the flood risk listAL4 9DB: not on the flood risk listAL4 9DE: not on the flood risk listAL4 9DH: not on the flood risk listAL4 9DJ: not on the flood risk listAL4 9DL: not on the flood risk listAL4 9DP: not on the flood risk listAL4 9DQ: not on the flood risk listAL4 9DS: not on the flood risk listAL4 9DU: not on the flood risk listAL4 9DW: not on the flood risk listAL4 9DX: not on the flood risk listAL4 9DY: not on the flood risk listAL4 9DZ: not on the flood risk listAL4 9EB: not on the flood risk listAL4 9ED: not on the flood risk listAL4 9EE: not on the flood risk listAL4 9EF: not on the flood risk listAL4 9EH: not on the flood risk listAL4 9EJ: not on the flood risk listAL4 9EN: not on the flood risk listAL4 9EP: not on the flood risk listAL4 9EQ: not on the flood risk listAL4 9ER: not on the flood risk listAL4 9ET: not on the flood risk listAL4 9EU: not on the flood risk listAL4 9EW: not on the flood risk listAL4 9EX: not on the flood risk listAL4 9EY: not on the flood risk listAL4 9EZ: not on the flood risk listAL4 9FG: not on the flood risk listAL4 9FH: not on the flood risk listAL4 9FJ: not on the flood risk listAL4 9FN: not on the flood risk listAL4 9FP: not on the flood risk listAL4 9FQ: not on the flood risk listAL4 9HA: not on the flood risk listAL4 9HD: not on the flood risk listAL4 9HE: not on the flood risk listAL4 9HF: not on the flood risk listAL4 9HG: not on the flood risk listAL4 9HH: not on the flood risk listAL4 9HJ: not on the flood risk listAL4 9HL: not on the flood risk listAL4 9HN: not on the flood risk listAL4 9HP: not on the flood risk listAL4 9HQ: not on the flood risk listAL4 9HR: not on the flood risk listAL4 9HS: not on the flood risk listAL4 9HT: not on the flood risk listAL4 9HW: not on the flood risk listAL4 9HX: not on the flood risk listAL4 9HY: not on the flood risk listAL4 9HZ: not on the flood risk listAL4 9JA: not on the flood risk listAL4 9JB: not on the flood risk listAL4 9JE: not on the flood risk listAL4 9JF: not on the flood risk listAL4 9JG: not on the flood risk listAL4 9JJ: not on the flood risk listAL4 9JL: not on the flood risk listAL4 9JP: not on the flood risk listAL4 9JQ: not on the flood risk listAL4 9JS: not on the flood risk listAL4 9JT: not on the flood risk listAL4 9JU: not on the flood risk listAL4 9JW: not on the flood risk listAL4 9JX: not on the flood risk listAL4 9LA: not on the flood risk listAL4 9LB: not on the flood risk listAL4 9LD: not on the flood risk listAL4 9LE: not on the flood risk listAL4 9LF: not on the flood risk listAL4 9LG: not on the flood risk listAL4 9LH: not on the flood risk listAL4 9LJ: not on the flood risk listAL4 9LL: not on the flood risk listAL4 9LP: not on the flood risk listAL4 9LQ: not on the flood risk listAL4 9LS: not on the flood risk listAL4 9LT: not on the flood risk listAL4 9LU: not on the flood risk listAL4 9LW: not on the flood risk listAL4 9LX: not on the flood risk listAL4 9LY: not on the flood risk listAL4 9NA: not on the flood risk listAL4 9NB: not on the flood risk listAL4 9NG: not on the flood risk listAL4 9NH: not on the flood risk listAL4 9NJ: not on the flood risk listAL4 9NL: not on the flood risk listAL4 9NN: not on the flood risk listAL4 9NP: not on the flood risk listAL4 9NR: not on the flood risk listAL4 9NS: not on the flood risk listAL4 9NT: not on the flood risk listAL4 9NU: not on the flood risk listAL4 9NW: not on the flood risk listAL4 9NX: not on the flood risk listAL4 9NY: not on the flood risk listAL4 9PD: not on the flood risk listAL4 9PE: not on the flood risk listAL4 9PG: not on the flood risk listAL4 9PH: not on the flood risk listAL4 9PJ: not on the flood risk listAL4 9PL: not on the flood risk listAL4 9PN: not on the flood risk listAL4 9PR: not on the flood risk listAL4 9PU: not on the flood risk listAL4 9QA: not on the flood risk listAL4 9QB: not on the flood risk listAL4 9QD: not on the flood risk listAL4 9QG: not on the flood risk listAL4 9QH: not on the flood risk listAL4 9QJ: not on the flood risk listAL4 9QN: not on the flood risk listAL4 9QP: not on the flood risk listAL4 9QR: not on the flood risk listAL4 9QU: not on the flood risk listAL4 9QX: not on the flood risk listAL4 9QY: not on the flood risk listAL4 9QZ: not on the flood risk listAL4 9RB: not on the flood risk listAL4 9RD: not on the flood risk listAL4 9RH: not on the flood risk listAL4 9RL: not on the flood risk listAL4 9RN: not on the flood risk listAL4 9RP: not on the flood risk listAL4 9RR: not on the flood risk listAL4 9RS: not on the flood risk listAL4 9RU: not on the flood risk listAL4 9RW: not on the flood risk listAL4 9RX: not on the flood risk listAL4 9SJ: not on the flood risk listAL4 9SL: not on the flood risk listAL4 9SN: not on the flood risk listAL4 9SP: not on the flood risk listAL4 9ST: not on the flood risk listAL4 9SU: not on the flood risk listAL4 9SZ: not on the flood risk listAL4 9TB: not on the flood risk listAL4 9TG: not on the flood risk listAL4 9TH: not on the flood risk listAL4 9TJ: not on the flood risk listAL4 9TL: not on the flood risk listAL4 9TN: not on the flood risk listAL4 9TQ: not on the flood risk listAL4 9TT: not on the flood risk listAL4 9TW: not on the flood risk listAL4 9TX: not on the flood risk listAL4 9TZ: not on the flood risk listAL4 9UD: not on the flood risk listAL4 9UE: not on the flood risk listAL4 9UG: not on the flood risk listAL4 9UJ: not on the flood risk listAL4 9UP: not on the flood risk listAL4 9UR: not on the flood risk listAL4 9UW: not on the flood risk listAL4 9XB: not on the flood risk listAL4 9XD: not on the flood risk listAL4 9XE: not on the flood risk listAL4 9XG: not on the flood risk listAL4 9XJ: not on the flood risk listAL4 9XL: not on the flood risk listAL4 9XQ: not on the flood risk listAL4 9XR: not on the flood risk listAL4 9XU: not on the flood risk listAL4 9XW: not on the flood risk listAL4 9XY: not on the flood risk listAL4 9YD: not on the flood risk listAL4 9YE: not on the flood risk listAL4 9YF: not on the flood risk listAL4 9YG: not on the flood risk listAL4 9YJ: not on the flood risk listAL4 9YL: not on the flood risk listAL4 9YQ: not on the flood risk listAL4 8JJ: very low flood risk onlyAL4 0NJ: low flood risk at worstAL4 0NQ: low flood risk at worstAL4 0NS: low flood risk at worstAL4 0PB: low flood risk at worstAL4 0RU: low flood risk at worstAL4 0RY: low flood risk at worstAL4 8DF: low flood risk at worstAL4 8HQ: low flood risk at worstAL4 8SB: low flood risk at worstAL4 0RT: medium flood risk at worstAL4 0NR: high flood riskAL4 0PA: high flood riskAL4 0PG: high flood riskAL4 8AA: high flood riskAL4 8BU: high flood riskAL4 8BZ: high flood riskAL4 8DT: high flood riskAL4 8EF: high flood riskAL4 8FJ: high flood riskAL4 8HH: high flood riskAL4 8HW: high flood riskAL4 8NJ: high flood risk St AlbansHarpendenHatfieldWelwynWheathampsteadWelham Green 5 postcodes at high or medium risk, outlined: this goes to AL4 8DT, the one with most homes and businesses at high risk5 postcodes at high or medium risk Map of every postcode in AL4, by flood risk Of the 787 postcodes in AL4 that ONS places, 13 have a home or business at high risk, 1 are at medium risk at worst, 9 are at low risk at worst, 1 are at very low risk only and 763 are not on the Environment Agency's at-risk list. One group of postcodes at high or medium risk is outlined: 5 postcodes at high or medium risk. Places named: St Albans, Hatfield, Wheathampstead. Drawn over roads, rivers and built-up areas. North is up; the scale bar is 2.5 km. A1081A1(M) St AlbansHatfieldWheathampstead
  • A home or business at high risk: 13
  • At medium risk at worst: 1
  • At low risk at worst: 9
  • At very low risk only: 1
  • Not on the at-risk list: 763
  • Outline: where 5 or more postcodes at high or medium risk lie together

Of the 787 postcodes in AL4 that ONS places, 13 have a home or business at high risk, 1 are at medium risk at worst, 9 are at low risk at worst, 1 are at very low risk only and 763 are not on the Environment Agency's at-risk list.

Each mark is a postcode's centre point as ONS gives it, not a building. Press one to see its postcode and open its page. A dashed outline shows where 5 or more lie within 150 metres of each other. It is not a boundary, and no boundary is drawn. Where marks overlap, the one first in the key is drawn; the counts include every postcode.

The middle of its postcodes: latitude 51.7738, longitude -0.2948. Open this area on OpenStreetMap

Source: Office for National Statistics (ONS) Postcode Directory, August 2026, loaded 20 October 2026, the centre point of each postcode; flood risk: Environment Agency, published 6 July 2026; roads, rivers and built-up areas: Contains OS data © Crown copyright and database right 2026. Drawn by us. Street map: Ordnance Survey, OS Open Zoomstack, Open Government Licence v3.0, drawn with MapLibre. How we use them

The postcodes at high risk

13 postcodes here have a home or business at high risk. These are the 12 with the most homes and businesses at that risk.

Beside each: how many of its homes and businesses the Environment Agency puts at that risk.

AL4 8DT11 at high riskAL4 8AA8 at high riskAL4 8BU5 at high riskAL4 0NR2 at high riskAL4 8HW2 at high riskAL4 0PA1 at high riskAL4 0PG1 at high riskAL4 8BS1 at high riskAL4 8BZ1 at high riskAL4 8EF1 at high riskAL4 8FJ1 at high riskAL4 8HH1 at high risk

Where the postcodes at high or medium risk lie together

  • 5 postcodes at high or medium risk, outlined on the map. AL4 8DT, is the one with most homes and businesses at high risk.

What broadband can you get in AL4?

Ofcom reports on 780 of the 787 postcodes in AL4. At 643 of them every home and business can get gigabit broadband, and at 6 some cannot get decent broadband (10 Mbit/s).

Postcodes where every home can get gigabit643 of 780
Postcodes where every home can get superfast718 of 780
Postcodes where some cannot get decent broadband6 of 780

Ofcom gives each postcode's share of homes and businesses, not how many there are, so these count postcodes. Each postcode page has its own figures. A provider's checker answers for one address.

Check one address on Ofcom's checker

Source: Ofcom, Connected Nations, Spring 2026, data for January 2026, Open Government Licence v3.0. How we use it

Is AL4 at risk of flooding?

24 of the 787 postcodes in AL4 have a home or business in an area at risk of flooding from rivers or the sea, the Environment Agency says. At those, it puts 40 homes and businesses in an area at high or medium risk.

Homes and businesses in an area at risk, at 24 of 787 postcodes High: 36Medium: 4Low: 82Very low: 24

High: 3.3% or more a year (1 in 30). Medium: 1% to 3.3% a year. Low: 0.1% to 1% a year. Very low: under 0.1% a year (1 in 1,000). Each band is the chance of flooding in any one year.

Homes and businesses in an area at risk of flooding from rivers or the sea, as the Environment Agency counts them, added up over the postcodes. It is for the land, not each building, and leaves out surface water, groundwater and sewers. Each postcode page has its own figures and its flood warning areas.

Source: Environment Agency, Risk of Flooding from Rivers and Sea (postcodes in areas at risk), published 6 July 2026, Open Government Licence v3.0. How we use it

What do homes sell for in AL4?

Homes in AL4 sold for a typical £640,000 in the 12 months to August 2026, across 305 sales, down 4.4% on the 12 months before, HM Land Registry's figures show.

£640,000 typical price, the 12 months to August 2026
£669,263 12 months to August 2025
▼ down 4.4% on the 12 months before
  • Detached £890,000 77 sales
  • Semi-detached £718,000 113 sales
  • Terraced £485,000 71 sales
  • Flat or maisonette £287,500 44 sales

Each bar is that kind's typical price, against the most expensive kind here.

Standard sales of homes at market value. A typical price is the median, the middle sale. Sales take weeks to be registered, so the last month or two are incomplete. Each postcode page gives the figure for its own postcode sector.

Source: HM Land Registry Price Paid Data, files dated 28 September 2026. Contains HM Land Registry data © Crown copyright and database right 2021. This data is licensed under the Open Government Licence v3.0. How we use it

Postcodes in AL4

Pick a sector, then a postcode. A sector is the district plus the next digit.

AL4 0291 postcodesAL4 8209 postcodesAL4 9287 postcodes
UK postcode format explained

Places in AL4

Towns and villages with postcodes in AL4, and how many each has here.

St Albans postcodes,413Wheathampstead postcodes,127Hatfield postcodes,1London Colney postcodes,1

Who covers AL4

How many of the district's postcodes in use fall under each council, constituency and police force area.

Councils

What council am I in?

Constituencies

  • St Albans432
  • Harpenden and Berkhamsted330
  • Hitchin12
  • Welwyn Hatfield10
  • Hertsmere3

Police force areas

  • Hertfordshire787

Next to AL4

AL3 postcode district AL5 postcode district All AL districts St Albans postcodes

"Next to" is by number: the districts before and after AL4 in the AL area.

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