Water pipe … dig-it-deep or through-the-roof?

[Dreadnaught]

I am planning my water connection. Water main is in the access road. My utility/plant-room is on the opposite side of my plot (15 m away) right across a root-protection area (RPA).

 

Which option to choose (see the image):

1. Dig a 15m long trench across my plot for the water pipe, 750 mm deep, right across the RPA, with my arboriculturalist breathing down my neck.
2. Dig a 3m short trench to the nearest part of the dwelling (a bedroom). Bring the water pipe inside the thermal envelope. Run a water pipe from there to the utility/plant-room through the posu-joist roof (its a bungalow with flat roof).

Any problems with Option 2?

 

 

 

Edited December 21, 2019 by Dreadnaught

[Temp]

Think you are allowed to mole a water pipe through a root protection zone.

[jfb]

1 hour ago, Dreadnaught said:

Any problems with Option 2?

you'll have warmer water from the cold tap?

[PeterW]

Use option 2 and insulate it well, and make sure you strap it to every joist as you go so it doesn’t move. 

[Dreadnaught]

10 minutes ago, jfb said:

you'll have warmer water from the cold tap?

 

Good point. But fortunately the roof joists will be full-filled with Warmcel insulation so the pipe will be very well insulated. 

I'd also run the pipe towards to the top of the insulation so its on the cooler side of the insulation.

(I would also use a continuous pipe run as it ran through the joists, no joints. I wouldn't want to risk any leaks or have any joints that I cannot access.

Edited December 21, 2019 by Dreadnaught

[jfb]

I suspect it will still be warm.  Think how quickly a lagged hot water pipe cools down (surprisingly quick I think). Also, what happens in summer if the pipe is near the top of the insulation?

[Russell griffiths]

I have just had a new main put in. 

They dug a couple of small holes and moled it surprisingly easy and cheap. 

 

If you go across the roof will you not also have to run it vertically up the wall before you get to the roof.  

 

My previous house had the main in the roof, so really you can do what you want. 

[Dreadnaught]

50 minutes ago, Russell griffiths said:

They dug a couple of small holes and moled it surprisingly easy and cheap. 

 

 

Interesting thought. Roughly how much was it and what distance @Russell griffiths? PM me if you prefer.

 

1 hour ago, jfb said:

I suspect it will still be warm.  Think how quickly a lagged hot water pipe cools down (surprisingly quick I think). Also, what happens in summer if the pipe is near the top of the insulation?

 

Those are good points. Thanks.

[JFDIY]

As others say, you will get warm water at your taps due to heat soak, we've got this in our place.

 

I would run a 10mm or 15mm pipe to the kitchen tap under the floor, either below the sub floor or in the insulation.  All other taps won't bother you so much, but on a hot summers day it's a bind to run off 10 litres or water to make a cold glass of squash for example.

 

 

 

 

[ProDave]

Our cold main comes up in the utility room at the corner of the house closest to the mains.  To get to the kitchen the cold runs up the wall, along in the void between downstairs ceiling and upstairs floor, then down into the kitchen.

 

There is no issue.  At worst the "cold" water will be 20 degrees if it has been standing in the pipe for a long time.  In winter that is a bonus as the raw water coming into the house is very cold.

 

Just keep the cold pipe well away from any hot pipes and lag it well.

[Temp]

Apparently you can hire moling kit..

https://www.diynot.com/diy/threads/impact-moling-new-water-supply-pipes.497296/

 

but poster says it's around £356 + vat for a weeks hire so not cheap. Would need three pits to go 15m.

 

[scottishjohn]

3 hours ago, jfb said:

I suspect it will still be warm.  Think how quickly a lagged hot water pipe cools down (surprisingly quick I think). Also, what happens in summer if the pipe is near the top of the insulation?

insultion  as in pipe lagging works both ways -keeing things hot or cold -not a problem in my mind .

other than drinking direct from tap --does it really matter if cold is a few degrees warmer  and thats a maybe 

 

It should be lagged anyway  and it still should be 750mm down anyway where ever it rtuns 

Edited December 21, 2019 by scottishjohn

[Russell griffiths]

My cost will probably be irrelevant but might give  a very rough idea. 

70m moled £700. Included pipe. Connection both ends extra. 

I would doubt anybody would come out for less than £350-400. 

As it would be two lads and the kit. 

[Conor]

No issues at all. Just ensure you fit a shut off valve at the point where the pipe enters the house, and is easily accessible.

[mvincentd]

Our blue 32mm pipe rises externally and converts to brass in order to penetrate the house, go through a stop tap, then converts to Maincor mlcp which threads 7m through utility room pozi's (currently not lagged and only half the sound insulation in the joists, but the utility is a steady 21deg'), then converts to brass to drop down wall into hard and soft supplies.  The closest hard water cold tap after this point is a further 20m at least...which is maincor mlcp lagged.  The only joints from stop tap to getting out of wall the tap is on are the two mlcp-brass junctions.

No problem with tepid temperatures at all.

Also option 2 has got to be cheaper than moling.

Do consider your aesthetic solution to running the external pipe up the side of the house to pozi height...or come inside low into a cupboard then run up.

[Dreadnaught]

Thanks everyone. Helpful, thoughtful and thought-proving as always!

 

This has got me thinking about gas too. What about gas? Would the same principle apply to bringing in the gas pipe straight in? Or is there some reason why that has to go underground?

[Russell griffiths]

Gas is completely different and you need to all to a gas safe engineer to see what you are ALLOWED to do with it.