waste pipes -

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Join Date: May 2008

Posts: 226

got an old building with multiple rooms and they all have wash basins in when one of the rooms empties their basin it causes other basins to bubble and spit out the plug hole.

there must be a blockage somewhere its just locating it, its only just started happening.

any ideas on locating, remidies gaining access to every room could be a nightmare

 

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Join Date: May 2009

Location: London/Lincolnshire

Posts: 1,461

At a guess the first place I would look is,if old and new waste pipes,is were the new plastic waste meets the old cast or lead waste

 

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Join Date: Feb 2009

Location: Wales, currently.

Posts: 83

Induced siphonage maybe? I had a discharge pipe that ran fine for a couple of years than one day, self siphonage of the trap!!! replaced the trap and with an anti siphon bottle trap and all has been well ever since.

Has the pipework been knocked around by any chance? could of affected the gradient of the fall, hope you figure it out, let us know anyway.

 

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Join Date: Mar 2009

Posts: 962

How many washbasins on how many floors?

Although this is not technically correct it may explain some thinking.

If they are all in the same position on different floors going up in a line then they may all be on the one stack. The spitting and sucking could be either syphonage or back pressure.

If the drain is blocked the trap seals will blow back, the bottom one the most probably. If the very bottom one blows then you know the blockage is somewhere either below where it joins the stack or underground. Either way you should have an access point somewhere either outside under a cover or inside at the base of the stack or even a sealed internal access cover.

Being an old building though I would check the main manhole access first and any other external access points to make sure they are clear.

If they are clear and obviously not blocked right up to the ground floor basin, then the problem could be a blocked vent.

As water is discharged into a pipe it forms something like a plug which pushes air in front of it and sucks air down the pipe behind it.

That is why if you have a blocked stack, and discharge a basin higher up the stack, the water from the basin pushes the air out, but it can't get out down the main drain if its blocked, so it pushes air and water out through the lower traps blowing their seals.

However if the vent is blocked and the water discharged can't suck air down the vent, it sucks the water seals out of the traps trying to get air that way.

We have had lovely fine weather of late and some times birds love to nest in the top of vents if there is no cage on the terminal, so nests can block the vent.

If you remove the top basin trap and let a couple of the lower basins go, you should feel the discharged water pulling in air down the top trap pipe, that is if the vent is blocked.

Please come on again if this is no use!

 

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Join Date: May 2008

Posts: 226

went back 2 days later the problem had gone

 

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Join Date: Mar 2009

Posts: 962

Possibly a blockage that has moved along the line?

Its rained and the birds having fledged the nest has been washed down the stack?

Interestingly, I have often wondered since drains are calculated to flow at least a quarter full when laid. Lets be frank soil waste in a drainage system has to float away in something.

What effect do modern conservation appliances have on them?

Surely with less water going down the flow rate has dropped below a quarter full and so may lead to blocked drains.

In the old days some councils used flushing tanks at the head of their drains and every so often let a tank full go to flush the drains. But that was when we had larger WC cistern capacities and possibly a lot more water going down drains than we seem to have now.

Just some thoughts. :-) :-)

 

love that comment bernie,
i think i said somewhere before 20 years ago at the ROCA factory on one of their update courses they told me if my horizontal waste run was too long according to current regs, simply go down to the next pipe size.
didnt make sense at the time, but has got me out of a few holes since!!

shaun

 

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Join Date: Nov 2008

Posts: 1,552

personally i think drain laying standards are crap these days especially on new builds 6 metre lengths of plastic wind up like bannanas after a couple of days laying arond on site no real leveling is done as long as its down hill it will do
durgos all over the place so little air flow thru when you lift the cover they stink even when theres no blockages
we had probably the worlds best sewage system in this country now its just diy quality in most places
its all in the name of cheap even the sanitary inspectors that come round from the council know little a bout the subject

 

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Join Date: Aug 2009

Posts: 508

Sanitary inspectors, whats them, now a-days, its a university kid all book learning and no practical, called a building inspector, you can run rings around them, one of them had the cheek to tell me he could not pass, float comprising of a wash hand basin then a couple of kitchen sinks, the anti siphon was in 11/4" copper, same as the basin waste, which jumped up to 11/2" copper for the sink wastes, he wanted me to run the anti in 11/2"copper, he had to go and check his little book when I said that I could start the anti siphon from the basin in 1" copper, then he moaned even more because he saw a drip of water on an access door on the C I soil stack, at the foot of the stack, the pans on the first floor were full to the brim with water, and I had a good 10' head of water behind the door, don't know why but he didn't seem to appreciate me reading him the rules to him