A water outage hitting Baldock is now set to spread to Letchworth, Hitchin and beyond as technicians isolate the burst main to carry out repairs.

The 16in outlet main at the Weston Hills storage reservoir remains under three metres of water, and supplier Affinity Water says it must isolate it from the network to fix it.

This could affect the supplies to the wider region, with the supplier anticipating that the SG4, SG5, SG6 and SG7 postcode areas could be hit – taking in Hitchin, Letchworth, Baldock and surrounding villages including Ashwell and Odsey.

A spokeswoman said: “We are sorry for the inconvenience this may cause, but please rest assured that this work is absolutely essential to enable to repairs to the water main to be carried out safely and restore customers’ supplies.”

There had been reports of a water leak in Pryor Road as early as Wednesday last week, but the problem became much worse yesterday evening – with most of Baldock left without running water.

Parts of Baldock and Letchworth were hit by a power cut at 11.45am this morning, with 210 properties still without electricity after an initial 626 were affected. It is not clear if this is connected to the water situation.

Affinity Water is handing out free water bottles on a grass verge beside London Road – postcode SG7 6NA – and in the car park at Knights Templar Sports Centre in Weston Way, postcode SG7 6EY.

Water is also being given out behind Tesco in the High Street. A station at Clothall Common has run out.

Affinity expect to provide a further update after 3pm.