A battle is on at the Kenley water treatment works to stop it from having to be shut down following the severe flooding in the area.
Firefighters are working around the clock at the plant in Godstone Road after setting up a high volume pump there at 9pm last night.
They will be there throughout the weekend pumping out the water which has come up from the underground river Bourne.
It is being pumped away 800m down the road towards Purley to alleviate the problem in the area.
Firefighters are pumping 5,000 litres of water a minute away from a stricken waterworks in Kenley.
The London Fire Brigade is using a high volume pump, capable of pumping 300,000 litres of water an hour, as well as a dedicated support crew who have been working through the night as part of the inter-agency response to protect the waterworks from flooding.
Crews are likely to remain at the scene throughout the weekend.
Sutton and East Surrey Water (SESW), which owns the centre, has put sandbags and other defences around key operating buildings and plant.
The site is currently supplying water to more than 46,000 properties and 116,000 people.
If SESW does have to shut down the site it is planning to supply its customers by re-routing additional supplies from other treatment works.
Network engineers are checking plans for supplying customers from other treatment works in case the site is flooded.
Operations manager Richard Rap said: “It’s touch and go at the moment with each new downpour adding to the possibility of the site being overwhelmed with flood water.
“We are doing all we can to protect our facilities and ensure the continued smooth operation of this vital strategic site.
”We have teams working 24 hours a day and they will continue to do so until the danger has passed.
“But the situation has and can continue to change dramatically at any moment.
“While we hope for the best we are prepared for the worst.”
The water company’s managing director said: “We would very much regret having to shut down Kenley treatment works and are doing all we can to make sure it does not happen.
“But this is a major incident and if the site is overwhelmed our overriding concern has to be to ensure the integrity and safety of our water supply."
Becky Carrier, who lives next door to the water treatment plant in Godstone Road, she was braced for losing her water supply and feared her family's ground floor flat could flood.
The 32-year-old estimated 24 flats and 12 houses had been cut off from the main road by the floodwaters.
She said: "We have been told we mght lose our water supply. People are quite worried but I'm more worried about the water coming into my home.
"You can't get anywhere at the moment. We are basically drapped in our houses. We can't get our cars in or out. There is a lot going on though - people arriving, pumping water, pipes being delivered."
The company is working with Croydon Council, the London Fire Brigade and the Environment Agency to ensure flood defence work and efforts to remove the water are coordinated as the inundation is affecting a wide area.
Fire Commissioner Ron Dobson said: "Firefighters have been working very hard throughout the night to pump water away from the facility and protect it from flooding.
"The water works supplies tens of thousands of homes in the area so our crews are working extremely hard to bring this incident to a quick and safe conclusion."
The A22 Godstone Road is still closed both ways between Kenley and Whyteleafe due to the flooding between the B2208 Croydon Road / Burntwood Lane / Woldingham Road / Succomb's Hill (Wapses Lodge Roundabout) and B270 / Whyteleafe Hill. Bus route 407 is on diversion.