ALL ABOUT DRAINS 

STORM & FOUL DRAINS

When you flush the toilet, take a shower or use the dishwasher, the waste water disappears round the U-bend, into your drain.

It leaves your property via a private drain which is your responsibility.

At the point your drain connects into a pipe which serves more than one property, or the drain runs beyond your property boundary, South West Water become responsible for it.

In the event of a blockage within your own private drain you will need to get it fixed by a private drain company.

In the event of a blockage within a sewer pipe serving more than one property, or outside your property boundary, South West Water will take care of it.

TYPES OF DRAINS

There are two systems of drainage that you need to think about:

• foul and 
• surface water 

          These two systems should be kept separate.

• Foul drainage carries the used water from toilets, sinks, basins, baths, showers, bidets, dishwashers and washing machines.

• Surface water drainage carries rainwater from hard surfaces

The above-ground system of gutters and rainwater pipes is referred to as roof drainage

The underground pipework is referred to as foul water sewers and surface water drains.

Building work on and around a sewer needs permission of the sewer owner.

Why do I need to know about underground drainage?

You may have to change your plans to suit the depth and location of the underground drain orsewer that you intend to connect to.

If you intend to build over or close to a public sewer, you will require written agreement from your sewerage undertaker, so you should consult the company at the earliest planning stage of your building work.

Building over an existing drain or sewer can damage pipes, so that they leak or block, potentially leading to odour nuisance, health problems and environmental damage.

It also makes it more difficult, time consuming and expensive to clear blockages and repair or replace faulty drains. 

If there is an existing drain below, or close to your proposed extension, it may need to be moved or protected, which is likely to increase the cost of your project.

The route of the drain should avoid obstructions (eg. ponds or outbuildings) and keep away from foundations, so may need to be longer and have additional access chambers, rather than running in a straight line.

In order to carry the flow and to avoid blockages, the drain or sewer that you intend to connect to generally needs to be at least 0.8m lower than the ground floor level. If it is less than this, you should seek advice from a builder, architect or drainage engineer.

How can I find out the location of underground drains and sewers?

Maps of public sewers can be inspected free of charge at the offices of the sewerage undertaker or local authority.

Private sewers and drains are not normally mapped and their location needs to be found in other ways, as described below.

Drain covers give an indication of drains below. By lifting the cover, it may be possible to see the direction, size and depth of pipes but do not enter the chamber (which can be filled with toxic gas) and ensure that the cover is replaced securely.

Locations of rainwater pipes, sanitary pipework stacks and external gullies can indicate where their underground drains are likely to run.

There are many firms which can carry out CCTV surveys that will indicate the condition of the drains as well as their location and depth.  Sonar tracing/tracking is used where thepipe is full of water/waste or mud as the camera cannot see in dirty muddy water.

You are strongly advised to seek advice from a builder, architect, drainage engineer or Local Authority Building Control before committing to or commencing work.

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