Who to Call for a Blocked Drain Out of Hours: Council, Thames Water or a Drainage Company?

Who you call for a blocked drain out of hours depends on where the blockage is, not on how bad it looks. A drain inside your boundary that serves only your property is yours, so you call a drainage company, or your landlord if you rent. A public sewer or a drain shared with neighbours outside your boundary belongs to Thames Water. A blocked road drain or street gully is the council's, or Transport for London's on a red route. Five minutes with a torch usually tells you which one you have.

Work out whose drain it is in five minutes

Look at what is blocked and who else is affected. Those two facts point to the right number in most cases, before you ring anyone.

• Only your property, inside your boundary. A toilet, sink or shower backing up, or an inspection chamber in your own garden or path full of water, with the neighbours unaffected. That is a private drain.
• Several properties at once. Neighbours on the same side of the road backing up too, or sewage rising in more than one house during or after heavy rain. That points to a shared drain or the public sewer.
• Water pooling in the road or on the pavement. A grated gully in the kerb that is not taking rainwater. That is a highway drain.
• A cover in the road lifting or overflowing with sewage. That is usually a public sewer manhole, not a highway gully.

If you can safely lift your own inspection chamber cover, it narrows things down quickly. Full to the top means the blockage is further downstream, possibly beyond your boundary. Empty while the house is backing up means the blockage is between the chamber and the house, which is almost always your drain.

Blocked drain on your own property: a drainage company

If the blockage is in a drain that serves only your home and sits inside your boundary, clearing it is your job, and at night that means a drainage company. Thames Water and the council will not come out for it.

When you ring, say where the water is appearing, whether the inspection chamber is full or empty, whether it is still rising, and whether you have another working toilet. Those answers decide whether it needs a van tonight or can wait for the standard daytime rate, and an honest drainage company should tell you if it can wait. Our emergency drainage service across London works on three time bands: 7am to 5pm is standard, 5pm to midnight is the evening rate, and midnight to 7am is the night rate. The current figures for each band are on our drainage pricing page, and the price is agreed on the phone before anyone sets off.

If the engineer finds on the night that the blockage is past your boundary, in a shared section or the sewer itself, they should stop, show you why, and tell you to report it to Thames Water. You should not be paying a private contractor to clear a public sewer.

Sewer or shared drain outside your boundary: Thames Water

Public sewers, and drains shared with other properties once they leave your boundary, are the water company's responsibility, and across London that is Thames Water. It runs a 24-hour line for sewer blockages and sewer flooding, and the number is on its website and on your bill.

Since October 2011, most shared private sewers and lateral drains in England were transferred to the water companies. So a pipe that carries your waste and your neighbours' waste, or your own pipe once it passes under the pavement, is generally theirs to clear. That holds even if another company supplies your water: in London, Thames Water deals with the sewers regardless of who sends the water bill.

Ring Thames Water rather than a drainage company when:

• Neighbours are backing up at the same time as you.
• Your own inspection chamber is full and the next chamber downstream, often at the front boundary, is full too.
• Sewage is coming out of a manhole in the road or pavement.
• Sewage is flooding into a home from the sewer during heavy rain.

If you are not sure, report it anyway. If Thames Water finds the blockage is in your private drain, it will tell you it is yours to clear. Our guide to who is responsible for a shared drain blockage covers where that boundary falls in more detail.

Blocked road drain or street gully: the council, or TfL

A blocked gully in the road or pavement belongs to the highway authority. In London that is your borough council, except on red routes, the major roads run by Transport for London, where it is TfL.

Highway gullies carry rainwater off the road. When one blocks, water pools across the carriageway and can run towards front gardens and basement lightwells. Both the councils and TfL take reports online and have out-of-hours numbers for highway emergencies such as flooding across a road. A single puddle over a gully can go in an online report. Water spreading towards homes or across a busy road is worth a phone call.

This is the one situation where a drainage company is not the answer even if you are willing to pay. Nobody should lift or rod a highway gully in the road without the authority's permission and proper traffic management. If water from the road is reaching your property, protect the doorway or lightwell, report it, and keep your own drains clear so they are not taking the road's water as well.

Most councils do not unblock private drains, so a search for a council 24-hour drainage service will usually lead you back to one of the other routes on this page. The exception is when the council is also your landlord.

Rented, council or leasehold home: your landlord's emergency line

If you rent, ring your landlord or letting agent first, even at night. For council and housing association homes that means their repairs line, which has an out-of-hours number for emergencies such as sewage backing up.

Private landlords are responsible for keeping the drains in repair, and most tenancy agreements say who to contact out of hours. Ringing them first matters for two reasons. Many landlords and housing providers have a contractor they send, and if you book your own they may refuse to reimburse you. And if the landlord cannot be reached and sewage is coming into the home, you have a clear record that you tried before arranging a call-out yourself.

In a block of flats, a blockage in a drain or stack that serves more than one flat is normally for the freeholder or managing agent to deal with. Check your lease or the notice board in the entrance for the emergency number. If only your flat's fittings are blocked and the stack is flowing, it is usually yours.

Home emergency cover: ring the insurer's helpline first

If you have home emergency cover, as a standalone policy, an add-on to your buildings or contents insurance, or through a bank account, ring that helpline before anyone else. Most policies only pay for contractors they send themselves.

Have your policy number and postcode ready, and describe the same things you would tell a drainage company: where the water is, whether it is still rising, and whether you have another working toilet. If the insurer cannot send anyone in a reasonable time, ask them to confirm in writing, or note the call reference and the time, that you can arrange your own contractor and claim the cost back. Without that, you may end up paying for the call-out yourself.

If sewage has already come into the home, take photographs before cleaning anything up. The steps for the first ten minutes are in our guide to sewage coming up through a drain or toilet.