Ultimate Guide to Replacing A Water Main Yourself!

Yay, we’ve ticked the first box on this years’ to-do list! We’ve officially finished the installation of our new water mains. (You can read more about our other plans for the year here.)

We still have the original lead water supply pipe leading into our house. Our water pressure is terrible – practically none existent. As part of our loft conversion, we have decided to get the lead piping leading into the house replaced. There probably wouldn’t be enough pressure to supply the loft with water otherwise.

We’ve been getting quotes for the job, but it’s really expensive – around £600, especially as it’s only a few meters of pipe that need replacing.

Well, we’ve decided to tackle the job ourselves! This is one of the scariest jobs we’ve undertaken so far!

Here’s our ultimate guide to replacing a water main yourself. (Don’t forget to check the rules and regulations where you live before attempting anything like this!)

This is what you will need if you want to replace your water main:

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A spade – Ideally a graft spade. No idea what that is? We didn’t either until very recently. Basically, it’s a spade that is very slim (about half the width of a normal spade) and long.

It just means that you can save time and energy – which you will also need a lot of – by digging a narrower trench. We borrowed the one we used from our builder, but a normal spade would work just as well.

25mm Blue Plastic Pipe – Which is the kind of pipe that is used for normal ground conditions. We got ours from a local DIY store.

Stop tap – In theory, we could have reused our existing stop tap, but as it was really old and leaky and needed a replacing. To go with the new plastic pipe, we’ve opted for a plastic stop tap, too.

Ducting – Where your new water pipe enters or runs underneath the building, it needs to be located in the duct. We used some old ducting that we had lying around, anything with a 100mm diameter should do.

Sealant for both ends of the duct – We used an expanding foam filler around the duct and some bubble wrap on the inside of the duct.

Insulation – Just any normal pipe insulation will be fine.

Builders Sand for lining the trench

Decent weather would also be really helpful, as you really don’t want your newly dug trench to fill up with water.

Connectors – 25mm to 15mm adaptor to connect your new plastic pipe to the existing 15mm copper piping in your house and possibly also some pipe sleeves, too

Our Experience

We started by digging the narrow trench from the front of the house to the garden wall. The trench has to be a minimum of 750mm deep to protect the pipe from frost.

Remember to be beware of any services like your existing water supply pipe, gas, electricity, TV, etc. If you can, try to locate them first.

We came across our mains electricity about halfway down the trench. Your new pipe has to be a minimum of 350mm away from any services.

Then, after digging the outside trench, we could start digging on the inside of the house. In our case there was already a brick missing in the wall where the existing lead water supply pipe enters the house, so we could just make the existing hole a bit larger.

Then we just pushed the ducting through the opening, leaving the existing supply pipe next to it.

You have to then fill the gaps around the ducting. We used a normal expanding foam filler on the outside and inside of the wall. Be careful not to get any filler in the duct – that has to be sealed separately.

You have to lay the new supply pipe up to the edge of your property boundary. In our case, this meant that we had to lay it up to the outer side of our garden wall.

At this point, we should mention that you are not allowed to dig open any part of the pavement yourself, but as we we’re only making a tiny hole which would later be filled and tarmacked over by our water company, we thought we’d just do it anyway.

Jan started by chopping away the tarmac with a hammer and chisel. The layer was really thin, so it was quick and easy to do.

Then, trying to keep the hole as small as possible, he removed the rubble and earth with a small spade.

Before laying your new pipe, you have to line the bottom of the trench with some sand.

The sand will provide a soft base for your pipe as well as cover any sharp stones that could damage it.

Then we could finally lay the pipe. We started on the pavement and pushed the pipe through the hole under the wall.

Getting the pipe through the hole and under the wall was a bit fiddly, but after that, it was really easy to push the pipe through the trench.

Make sure that you have sealed both ends of the pipe as you don’t want any dirt to get into it. Our pipe came with little stoppers which we covered with tape to make sure they couldn’t budge.

From where the pipe enters the building you will have to insulate it. We used standard pipe insulation to cover the pipe both in the duct and cellar. Then all that’s left to do is seal the opening around the new pipe. We just used some bubble wrap that we squashed into the duct.

Of course, we also filled the hole we’d made on the pavement, too. You have to leave a long piece – about 1m – of the pipe at the edge of your property boundary so that it can be connected to the mains supply.

After preparing everything, we then had to wait for the work we’d done to be signed off by the utility company. About a week later the inspector came around and checked everything – and was happy with what we’d done!

Needless to say, we were very relieved and really happy that we could finally fill in the trench running through our front garden.

Then came the wait… skip forward by about four weeks…

In the morning we turned the water off at the road. Then our lovely plumber (thanks Steve) came and removed the old pipe and connected the new stop tap and pipe. The utility company then dug up the pavement and connected our pipe to the main water supply.

Here’s a sneaky picture I managed to snap for you.

A day after our new supply pipe had been connected, the company came back to fill in the hole, a day later, they came back again and tarmacked the pavement and another day later they came and picked up their barriers. It all seemed a bit bizarre.

Our utility company offers a lead replacement scheme. They will connect and replace the lead pipe for free if you replace the lead pipes up to your property boundary. Basically digging a hole has saved us about £500.

As we’d mentioned before, we were really daunted by doing this job ourselves. It actually turned out to be so much easier than we’d expected and we wish we’d done it sooner. Not only is the water supply much healthier, but the water pressure has also dramatically improved!

Are there any jobs you’ve been worried about doing yourself? Where do you draw the line between trying to do something yourself and paying someone to do the work for you? Have you attempted replacing a water main yourself?

It’s important to check rules and regulations where you are. We did this work after speaking to and in close cooperation with our utility company who checked all of our work. You will only be allowed to work on your property! If you’re unsure of anything get professional help!