Blocked pipework in potable water supply

[takechair]

Dear all,

I'm hoping you can help with this because our plumber is trying hard but he's struggling to solve the problem.

I'll describe the system. The water enters the apartment in a washing machine cupboard. At the inlet and at the washing machine the pressure is high. The pipework then branches one way to the kitchen and another way to the two bathrooms. Water pressure at all other faucets is very low, both for hot and for cold.

Now about 2 years ago the pressure was very low at the faucets. The plumber came and he took the faucets off the wall and the pipes were backed up with silt. He flushed all the silt out and everything was fine. I think this happened again about a year later. Cleared the silt. Everything fine.

So now the tenant has been away for 6 months. When she came back she has this problem with the water pressure. The plumber has tried what he did before. Couldn't find any problem. Our assumption is that since the tenant has been away for so long the silt in all the pipework has solidified at some point between the faucets and the main inlet. The plumber went back there yesterday and he's tried using the water from the washing machine connection to back flush the pipework from one faucet into the bath. This didn't help. He's tried running all taps at the same time. Didn't help. Cleaned all aerators and tap filters. Hasn't helped.

Does anyone have any idea how we could potentially clean the inside of the pipework? Obviously this is more difficult since it's potable water.

Thanks. Just let me know if any questions.

Dan

 

[Aquarius]

First off I’d be looking at any reduced bore isolation valves. If there aren’t any, then only solution I think would be is to start chopping out sections of pipe, to inspect or renew?

Is any of it on a boosted supply?

 

[brian ross]

Im only a DIY user, but if you get this fixed get your plumber to install a Y-strainer after the stopcock, at least that way the crap will get caught in one easy to service place. We have one here and every 6 months to a year i clear it out, tiny fragments of the cast iron main under the road, the odd bit of black plastic etc, its amazing whats in the water!

 

[steadyon]

1. What do you mean by "silt"?
2. Is it dirt coming in from the water mains, or is it limescale build up?
3. If dirt from the water mains, fit a "Y" strainer at the point of entry and make sure it is regularly cleared.
4. If limescale, the only long term solution is an ion exchange type water softener. Not always practical in a flat.
5. Neither option helps with the current problem. As Aquarius says:
5a. Look for typical blockage points like isolation valves and sharp bends / elbows.
5b. Cut the pipes, working backwards from the blocked outlets.
6. Before doing the above, it would be worth investigating exactly what set up you have for hot and cold water. Could be the non-kitchen outlets are tank fed, in which case the issue could be a simple air lock.

 

[takechair]

Hi,

Thanks for your help guys really appreciated.

Yes that's a good idea to check the reduced bore isolation valves. There's a lot of those on the system and I'm not sure if he's done that.

I'm not sure if it's a boosted system but I will find out.

By silt I mean this soft mushy material a bit like mud but sandy coloured. Pretty sure that's not limescale because limescale would be hard right.

Well I'm not sure where the material comes from. I know quite a few other apartments in the building and none of those have had any problems. I'm guessing that it's coming in from outside the apartment but how that can happen without affecting other apartments I'm not sure. Either that or it was already in the pipe work in the apartment and it's slowly working its way out. It's a bit of a mystery.

Yes I said that to the plumber about the Y filter because I was saw those on Google before. But he said he thought the silt would just go through them. But thinking about it I think that can't be right because it was backing up from the tap filters previously.

No I'm pretty sure all the water outlets are fed in the same way because they all have the same stop valve.

I'm going to go there with the plumber on Saturday so I'll let you know how I get on!

Thanks again,

Dan

 

[steadyon]

What sort of hot water system do you have? I ask because there have been reports (not sure if they have been verified) of the plastic disc in MegaFlo unvented hot water cylinders degrading and forming granules. However, don't see how they could have got into the cold side.

 

[Chuck]

By silt I mean this soft mushy material a bit like mud but sandy coloured. Pretty sure that's not limescale because limescale would be hard right.

Does it feel sandy or slimey? If its the latter it is (probably) bacterial in nature. If this is the case, the whole system needs flushing with bactericide and checking for things like dead-legs where stagnant water could collect.

Your plumber should be able to identify the problem. If in doubt there are laboratories that you can take/send a sample to for analysis. Consult them before buying so you get the right type of test. Also check the 'water quality' section of your water supplier's website.

 

[takechair]

Hi,

Thanks Steadyon it's just standard system with a combi boiler. The apartments are about 10 years old. There's no unvented tank actually the pressure is good when the system is operating normally.

That's right Chuck its very slimey. That's interesting I didnt realise that bacteria could build up to the extent it could block pipes. I won't mention that to the tenant yet or they will freak out! I don't think it can be harmful because its been like this for a few years. I will ask the plumber to check the pipes for dead legs. Although I guess its also possible the dead leg could be outside the apartment. If I can find some more of that sludge I'll take a sample of it.

I'll let you know how it goes.

Thanks

Dan

 

[Chuck]

That's right Chuck its very slimey. That's interesting I didnt realise that bacteria could build up to the extent it could block pipes.

There may be other explanations for 'slimey' but the fact it's (a) in the cold pipes, (b) seemed to build up whilst the system was not used for several months and (c) other nearby dwellings are not similarly affected taken together lean me towards some sort of bacterial or biofilm problem.

Might be worth contacting your water utility and asking them for advice and to check the supply. The problem has got to have started somewhere and their engineers really know their stuff.

Do let us know how you get on. These problems are relatively uncommon so it's interesting to learn from others' experience.

 

[takechair]

Hi

Just to update you on what happened with this one. Bit of an anticlimax I'm afraid. When we were due to go there on Saturday the tenant said she didn't think the plumber would be able to fix it and it was too much hassle so she didn't want us to go anymore. She's OCD so I think she has to do a full deep clean every time someone goes there. Anyway that's fine it's a hassle for us as well!

We will fix this problem but after she moves out in a few months. Thanks so much for all the help everyone I feel pretty confident now we'll get to the bottom of it. I will try to update here when we eventually do discover the source of the problem.

Thanks,

Dan