New connection - low pressure

[finishthehouse1day]

When we had an extension built we added an outside 'privy' in a separate building a few feet from the house. The builder left us with the blue underground pipe (20mm?) leading from the kitchen to the loo, about 20', for us to connect up.

We've fitted the loo and sink today and made the connection to 15mm pipe to feed the loo & sink - everything seemed really straightforward but we can't get any water pressure to the 'privy' at all. There are no blockages and we're certain there are no leaks. There's a bit of pressure when we first turn on the tap but after a few seconds it trickles to nothing. We've checked the service valves and all are working (and fitted the right way!). The water pressure here generally is pretty good. We've tried turning up the pressure to the whole house but it had no effect.

Can anyone tell us where we've gone wrong?

Ta!

 

[chrishutt]

If you have mains pressure at one end of the poly pipe and nothing at the other, something is blocking it. If you're really sure all the valves are open then it must be something inside the pipe, although this is unlikely.

 

[finishthehouse1day]

Thanks but I'm sure it's not a blockage - we disconnected the pipework at each end and rigged up a hose so that we could blast a good pressure of water through and it came out fine at the other end. When we connected it all back up though, no pressure again. We've taken off the valves, which are compression fittings, and visually checked them and they are fine.

I was wondering if it's because we've gone from 15mm pipe back up to the blue, plastic underground 20mm pipe? Could this be something to do with a loss of resistance?

 

[chrishutt]

What you say doesn't add up. Have you got free flow at the house end of the pipe? If yes, have you got free flow at the outhouse end of the pipe? If not, the pipe is blocked. But If yes, the obstruction is further downstream. Just try to think logically about it.

 

[meldrew's_mate]

...There's a bit of pressure when we first turn on the tap but after a few seconds it trickles to nothing.

Definately indicates a blockage, or service valve nearly off. If you've cheched the pipework then check the tap(s) and dismantle/clean the WC filler (Torbeck?).
My money is on a defective, blocked, or nearly closed connection in the house for exactly the reasons quoted above. Re-check the supply from the house by disconnecting the blue plastic at the house, connecting a hose to the supply, and running it into a watering can. If I'm right the flow here will quickly drop too.

 

[Nige F]

Thanks but I'm sure it's not a blockage - we disconnected the pipework at each end and rigged up a hose so that we could blast a good pressure of water through and it came out fine at the other end.

Leave it connected like that........in the winter you won`t want the privy.....believe me I`ve used them .......Yeah BUT your temp. working hose wasn`t connected TO the SAME point as the blue pipe was it ....reconnect in exactly same place as blue pipe .....then it will prove without dobt ....where the prob. lies