River Cray Flooding in St Mary Cray and St Paul's Cray

Homes near the River Cray in St Mary Cray and St Paul’s Cray do carry some flood risk, from two directions: the river itself, and groundwater rising out of the chalk after a long wet winter. Bromley Council’s records show river flooding at St Paul’s Cray in September 1968 and August 1977, flooding across Cray Valley East in winter 2013, and groundwater flooding at St Mary Cray in winter 2014. Check your postcode’s long-term risk on gov.uk, sign up for the Environment Agency’s free warnings for the Cray, and, if water has ever come up through your drains, ask about a non-return valve.

Where the Cray comes from

The Cray is a chalk stream. It rises at Priory Gardens in Orpington, from a spring-fed pond where the chalk meets the clay, and runs north through St Mary Cray, St Paul’s Cray and Foots Cray, through Foots Cray Meadows and on to North Cray, Bexley and Crayford, where it joins the Darent.

Being a chalk stream matters. Its flow depends heavily on how much water is stored in the chalk under the North Downs. After a very wet autumn and winter, the chalk fills up and springs break out in places that are normally dry. That is groundwater flooding, and it behaves differently from river flooding: it rises slowly, lasts for weeks, and comes up through floors and cellars rather than in through the door.

The flood history, from the council’s records

Bromley’s Strategic Flood Risk Assessment lists these events in the Cray valley:

• September 1968: widespread river flooding across the borough, with St Paul’s Cray among the worst hit.
• August 1977: flooding at St Paul’s Cray in the Darent and Cray catchment.
• Winter 2013: flooding in Cray Valley East from groundwater, the watercourse and surface water combined.
• Winter 2014: groundwater flooding at St Mary Cray, on roads, in gardens and in below-ground car parks, including the Tesco car park.

The same winter, groundwater came up in West Wickham, Orpington and Biggin Hill too. Bromley later joined neighbouring boroughs in a groundwater partnership after major groundwater emergence in Bromley and Croydon in 2014.

How to check your risk today

• Long-term flood risk: search “Check your long term flood risk” on gov.uk and enter your postcode. It shows river, surface water and groundwater risk separately.
• Flood warnings: the Environment Agency has a warning area for the “River Cray from St Mary’s Cray to Crayford including Hall Place”. Sign up on gov.uk (“Sign up for flood warnings”) for a free call, text or email.
• Your own history: ask neighbours who have lived there a long time. Groundwater tends to come back in the same places.

Preparing your home

1. Sign up for the free Cray flood warnings.
2. Find your stopcock and consumer unit, and make sure you can reach both.
3. Photograph each room now, so you have “before” pictures for an insurer.
4. Keep valuables, documents and sentimental items upstairs or on high shelves.
5. Ask a plumber about a non-return valve on your drain if water has ever backed up through a toilet or gully.
6. Keep pan bungs or a toilet seal for downstairs toilets during a warning.
7. Clear gutters, gullies and yard drains before winter.
8. Check your insurance covers flood, and note the excess.

A non-return valve lets waste water out of your house but stops sewer or flood water coming back in. In heavy rain or high groundwater, the drains in a low-lying street can surcharge, and the lowest toilet or shower in the house is where it appears.

If groundwater appears

Groundwater does not respond to sandbags in the way river water does. It rises through floors, under doors and into cellars. Pumping it out can be pointless while the water table is high, and can even damage foundations if done too hard. Get advice from Bromley Council, which is the Lead Local Flood Authority for the borough.

Check it is really groundwater, not a leak: read your water meter, use no water for an hour, and read it again. If it has not moved, the water is from outside.

After a flood

• Photograph everything before clearing up.
• Ring your insurer for a claim reference.
• Keep electrics off until an electrician has checked wet circuits.
• Have any gas boiler or appliance checked by a Gas Safe registered engineer before use. We do not work on gas.
• Have drains checked for silt and debris, and the hot water cylinder and immersion checked if they were wet.
• Run the cold kitchen tap until it runs clear.

Our insurance help page explains the report we write for insurers. On the Bexley side of the river system, our guide to River Shuttle flood alerts in Sidcup and Blackfen covers what alerts mean.

When to call

Call us if water is backing up through drains or toilets, a pipe is damaged, or you need the plumbing checked and written up after a flood. We handle insurance claim work in the Petts Wood and Cray area and blocked drains in Petts Wood and the Crays.

Need a plumber now?

Call 07868 281022 and tell us your postcode, where the water is coming from, and whether the water and electrics are off. We agree the price with you before any work starts.