Flood ยท Piece
After a flood: gas, water and electrics
A boiler after a flood should not be used until a Gas Safe registered engineer has checked it. Have electrics and water checked before they go back on too, and never touch switches while standing in water.
Most useful for: Anyone going back into a flooded house, flat or let in Cambridgeshire
Compiled from the sources at the end. Updated .
Falling water is not the same as a safe house. Wiring, boilers and pipes can look untouched and still need checking, and flood water may contain sewage. The order below follows GOV.UK's after-flood advice and its guidance for during a flood.
What should happen first?
- Confirm it is safe to return before going in.
- Never touch a switch, socket or appliance while standing in water.
- Do not turn gas, electricity or water back on until they have been checked: gas by a Gas Safe registered engineer, electrics by an electrician or your network, water by your water company.
- Contact your insurer and photograph the damage before anything is thrown out.
- Book a Gas Safe registered engineer for the boiler and other gas appliances, and an electrician for the electrics.
Smell gas: use no switches and no flames, open doors and windows, leave the building, then call the National Gas Emergency Service on 0800 111 999 from outside. Carbon monoxide alarm or suspected CO: everyone out, and call the same number from outside. With symptoms, ring NHS 111, or 999 if someone is struggling to breathe, suddenly confused or unconscious. Do not go back in until told it is safe.
Who checks the boiler?
A Gas Safe registered engineer, and nobody else. HSE says it is illegal to use an appliance you suspect is unsafe, and a boiler that has stood in flood water falls into that doubt. Do not open the casing, dry it out yourself or try the controls to see whether it fires.
Check the engineer's card before work begins, or ring the Gas Safe Register on 0800 408 5500. In a rented house, ask the landlord to arrange this. A record from the annual gas check done before the flood does not replace it. If the engineer advises moving the boiler during repairs, the resilience page covers what that involves.
What about the electrics?
Ring 105 about a power cut or an electrical hazard, a number GOV.UK gives for floods. Inside the house, leave the wiring to an electrician. Power returning to the street tells you nothing about the circuits in your walls.
Any replacement consumer unit or new circuit is notifiable under Part P, so ask the electrician how it will be certified.
Is the tap water safe to drink?
The Drinking Water Inspectorate says mains water is usually unaffected by flooding. If the colour, taste or smell changes, call your water company and boil the water or use bottled in the meantime. The company name is on your bill.
Private supplies are different: do not use one until it has been checked. They exist in South Cambridgeshire, and the district council regulates them.
What if sewage came in?
Treat flood water as if it contains sewage, which GOV.UK warns it may. Report an overflowing sewer to your water company, as Cambridge City Council also advises. Payments can apply where effluent enters a building, and the sewer flooding page has the figures.
| Problem | Who | How |
|---|---|---|
| Gas smell or suspected carbon monoxide | National Gas Emergency Service | 0800 111 999, from outside |
| Power cut or electrical hazard | Electricity network | 105 |
| Overflowing sewer | Your water company | Number on your bill |
| Change in tap water | Your water company | Number on your bill |
| Flood warnings and risk | Floodline | 0345 988 1188 |
| Live flood or main river blockage | Environment Agency | 0800 80 70 60 |
| Suspected asbestos | Council environmental health | Council website |
Before old plaster and boards come out
Drying out an older house can start with stripping walls, and this is where it needs more care. HSE says any building built or refurbished before 2000 may contain asbestos, and lists boards around boilers and in airing cupboards, bath panels and cement flues among the places it can be in a home. Insulating board is hard to tell from plasterboard.
Do not break, drill, sand or sample a board or coating you are unsure of. Tell every contractor before they start, because they should stop if they suspect it, and ask council environmental health for advice. Read asbestos around old boilers and tanks first.
Your insurer may want to see damaged materials, and listed buildings bring their own rules. In a listed house, ask the conservation officer before original plaster or joinery goes, since South Cambs guidance says consent is likely to be needed for minor alterations and possibly even repairs.
Who does which job after a flood
- Saying the gas and boiler can be used again
- A Gas Safe registered engineer
- Saying the electrics can be used again
- An electrician or your electricity network
- Tap water that has changed
- Your water company
- Claim and photographs
- You and your insurer
- Repairs to installations in a rented home, apart from flood reinstatement
- The landlord, under section 11
Other questions on this
Can I run the boiler for a few minutes to help dry the house?
No. Leave it until a Gas Safe registered engineer has checked it. A short test run is exactly what the checks exist to prevent, and using an appliance you suspect is unsafe is illegal.
Do I have to boil tap water after every flood?
Not automatically. The DWI says mains water is usually unaffected, so boiling or bottled water applies if the colour, taste or smell changes, while you wait for your water company's advice.
Does the landlord have to pay for flood reinstatement?
Section 11 of the Landlord and Tenant Act 1985 does not extend to flood or fire reinstatement. Installations for water, gas, electricity, heating and hot water still come under the repair duty, so talk to your landlord and look at the tenancy.
Where can I get impartial advice on recovery?
The County Council names the National Flood Forum for impartial advice. For the flood risk itself, start with the long term check.
Sources, read 4 November 2026: GOV.UK: after a flood; GOV.UK: help during a flood; Drinking Water Inspectorate: flooding; HSE: domestic gas questions; HSE: carbon monoxide; NHS: carbon monoxide poisoning; HSE: Gas Safe Register; Approved Document P; South Cambs: private water supplies; Cambridge City Council: emergencies; HSE: asbestos location and materials; HSE: asbestos diagrams, domestic; HSE: asbestos questions; HSE: why asbestos is dangerous; South Cambs Listed Buildings guidance, 2009; Landlord and Tenant Act 1985, s.11; Cambridgeshire County Council: preparing for flooding.