Plumber/drainage specialist - help please

[sunspot]

Thanks to all for your suggestions.

As suggested by The Aquila, we phoned Dave at Jetwash. He came this morning. Ran a camera to one of the WCs. No blockage.

Dave's diagnosis: Our main contractor installed preformed plastic manholes of the kind used in the UK. In these you need to fit non-return valves to prevent smells flowing back up the pipework. Main contractor did not do this, so smells are entering the house from the pipework. Dave will order and fit non-return valves for us.

For the benefit of people reading this thread in the future:

- Dave said that one should be able to put toilet paper in reasonable quantities down WCs with 4-inch pipes, no problem.

- All external manholes should have their edges greased to prevent smells emerging outside. This is a mix of engineering grease and sand. It forms a smell seal around the edge but does not make it harder to open the manhole if needed. It is UK regulations that, whenever a manhole is opened, it should be regreased.

- Don't let your plumber run mutiple outlets (WC, basin, shower, etc) into a single pipe going out into a manhole. They do this to save money. Try to get at least your WC on a separate pipe. I did try but met with such resistance, I gave up. Do not give up.

- Similar to Jim B, we had thought the fall of sewage pipes should be 1:100. Dave says he uses 1:4 in all his work. The shallow slope in our house may have caused the blockage we had a few weeks ago. We will have to be careful. For others contemplating work, perhaps you should do some research so you get the right slope.

- I would advise anyone building/renovating a house to consult with Dave on the specs of the sewage system in advance. Many thanks to The Aquila for recommending him.

I am happy to answer any questions arising from this thread.

[Jim B]

Thanks to all for your suggestions.

As suggested by The Aquila, we phoned Dave at Jetwash. He came this morning. Ran a camera to one of the WCs. No blockage.

Dave's diagnosis: Our main contractor installed preformed plastic manholes of the kind used in the UK. In these you need to fit non-return valves to prevent smells flowing back up the pipework. Main contractor did not do this, so smells are entering the house from the pipework. Dave will order and fit non-return valves for us.

For the benefit of people reading this thread in the future:

- Dave said that one should be able to put toilet paper in reasonable quantities down WCs with 4-inch pipes, no problem.

- All external manholes should have their edges greased to prevent smells emerging outside. This is a mix of engineering grease and sand. It forms a smell seal around the edge but does not make it harder to open the manhole if needed. It is UK regulations that, whenever a manhole is opened, it should be regreased.

- Don't let your plumber run mutiple outlets (WC, basin, shower, etc) into a single pipe going out into a manhole. They do this to save money. Try to get at least your WC on a separate pipe. I did try but met with such resistance, I gave up. Do not give up.

- Similar to Jim B, we had thought the fall of sewage pipes should be 1:100. Dave says he uses 1:4 in all his work. The shallow slope in our house may have caused the blockage we had a few weeks ago. We will have to be careful. For others contemplating work, perhaps you should do some research so you get the right slope.

- I would advise anyone building/renovating a house to consult with Dave on the specs of the sewage system in advance. Many thanks to The Aquila for recommending him.

I am happy to answer any questions arising from this thread.

Sunspot
I don't want to get into an argument but the slope is 1 in 100 or 1/4" per foot.
The Non Return Valve is used in high water table areas were there's a tendency for flood water to back up the the pipe.
I worked 55 years in the Construction Industry and quite a few of those were for North West Water Engineering.

[Kili01]

Hi Sunspot, glad that Dave at Hydrajet has helped you.
I also recommended them. Sorry that your original contractor didn't do the job as well as he should. I remember that in our Kamares house, all our 3 loos had their own soil pipes. That plus using the bigger pipes seemed to add up to a trouble free waste drainage system. We never needed anything additional added. But as I said originally, it seems that you still need to keep an eye on what plumbers ( and electricians) are doing! If possible!
Dee

[trevnhil]

It is always best if you can to oversee what drainage is being put in during the build.. But of course, if you buy a ready-built property you cant do that.
Our three bathrooms each have a separate 4" pipe into the main drainage run, alongside the bungalow which is also 4"
We also have 3 washbasins, two sinks, 2 showers, 1 bath, and a washing machine that all empty into to main 4" outside underground pipe system..

[Jim B]

I'll put it simply, that type of check valve (non- return) does not form an air tight seal unless there is back pressure against the hinged disc even if they are spring assisted. This means fitting a check valve will not stop vapours returning through the pipe.
What stops the smells are the water traps in the sinks, showers, toilets and wash basins. If the water trap either evaporates with the heat or the corrugated plastic pipe they use to connect wash basins baths etc aren't shaped correctly to form a water trap then vapours pass through into the house.

[Princebytor]

I'm no expert but I'm with Jim. I was told that the water traps stop the smells and on the one occasion we had a niff in the bathroom, the plumber immediately pointed to a perished rubber seal where the pipe below the water trap enters the wall. He replaced this and we have never had a smell since.

[Kili01]

Thanks for that info, Princebytor. I wonder if this is the cause of the 'niffy smell which is a problem once the weather gets warmer. It seems to come from somewhere in the plumbing to both toilets. But when I told Hydrojet about this smell, I was told that when I have their non return valve fitted it should cure the smell.

Dee

[Jim B]

Thanks Princebytor. Over the years I've been involved with installing, servicing and testing non-return valves from 6mm to 4 metre in size and never come across one that was manufactured to stop smell.

[Jamboal]

Have worked in the plumbing/water industry and here never heard of non return valves being used in domestic plumbing systems to prevent smells, as has been mentioned that is the job of the traps. It would be worth greasing the seating of your outside manhole covers to create a seal as this is a problem with some of the metal type here, smells can enter the house through open windows or vents and it’s an easy and cheap fix.

[Kili01]

Thanks for all your advice! It seems that there are some very knowledgeable people on here.
It also seems as if my problem with smells from the drainage system could be alleviated by a good plumber, rather than an expensive non return valve.

Dee

[jagwheels]

I hope Sunspot has has got her problem resolved but two things when we first visited Paphos. Our hotel had a bucket in the toilet for putting your toilet paper in. New experience to us but abided by the rule. Speaking to some other guests they said we just ignored it. We also visited a Greek Island on one occasion & same request was made. Secondly again on our first few visits sewage could be smelt on the way from our hotel to restaurants around the triangle. Within a few years the smell had vanished so something must have been done to resolve the problem

[sunspot]

I am delighted to report that the installation of non-return valves in 2 manhole chambers has eliminated all sewage smells. We are vastly relieved. Bravo to Dave at Jetwash. Highly recommended. 96 207 155. Thanks also to Paphos Life and all who responded to my SOS.

[trevnhil]

I have never heard of the non return valves before, but I am glad that your problem is sorted.

[Jim B]

I have read, watched videos and looked at the technical data on several drainage non return valves and as I said they are for preventing flooding or backflow in drains, not specifically to prevent odours.
Anyway if your happy, that's good.