A failure at a water supply plant has left properties across West Sussex with little or no water.
Southern Water said the outage followed low levels of chlorine at its Hardham water supply works.
The company said 20,000 customers were affected and expected the number to grow to 40,000 throughout Sunday.
Southern Water said three bottled water stations had opened and deliveries would be made to vulnerable customers.
A fleet of 19 tankers was supporting hospitals and areas most in need of supplies, the company said.
Reservoirs ‘refilling’
On Sunday, the company said chlorine levels had stabilised and the plant was now operational again.
It said the next steps were to refill the reservoirs and recharge the network, which would continue through the afternoon and into the evening.
Customers were warned they may expect intermittent water supply during the recharge, which was normal, and there was no reason for concern.
The company said if plans progressed as anticipated, customers should see water return within the next 24 hours.
The company had said Horsham, Billinghurst, Broadbridge Heath, Pulborough, Codmore Hill, West Chiltington, Wisborough Green, Rudgwick, Loxwood, Barns Green and Slinfold had all had supplies disrupted.
‘High standards’
It said: “Our sites operate to the strictest standards for water quality and are designed to automatically shut down well in advance of any risk to our customers.
“The incident was caused by unusually low levels of chlorine being detected at our Hardham water supply works.
“Chlorine is an important part of our standard treatment processes used to ensure water quality meets the very high standards set.”
The outage affected those who received their water from the Upper Nash and Itchenfield reservoirs.
Andrew Griffith, Arundel and South Downs MP, said: “It is at times like these when the mark of a good organisation is excellent communications and a rapid response to fix things or to help those most impacted.
“We need our local councils and Southern Water to step up and help households who have already been without even a basic water supply for 12 hours.”
Any vulnerable customers who need water can sign up to the company’s priority services register.
The bottled water stations can be found at Billingshurst Football Club, Lidl in Billingshurst, Toat Cafe & Hand Car Wash in Pulborough and Horsham Park and Ride.