We moved into our house last year and have had constant problems with smelly drains. On investigation we found none of the showers have P traps. So in the process of digging under the house to install these. But one thing i discovered talking to a number of plumbers is that no one understands the need to vent a drain. Our house has no vents.  I may get the plumbers to install air admittance valves as impossible to install vents. I'm interested to hear from people who self build whether this is something they specified in their build. 

They never heard of soil pipes here. We tried to vent our system with a mammoth fan and a very large outside 4" soil pipe.....it should have worked in theory, sucking the miasma out of the septic tank, but it didn't. On the bright side the pipe is very long and there is no smell now, even when it rains and the water table rises and pushes back on some of the drainaways.

I can only confirm that many Thais don't understand the idea of vents.

Like: It's just a pipe to nowhere, we don't need it.

And even when I showed some presumably experts a graphic which explains it, they just don't understand the concept.

 

 

27 minutes ago, retarius said:

They never heard of soil pipes here.

Yes they have. A soil pipe is a pipe use to remove soiled water. They are on toilets, sinks and showers. We know them as U bends.

You don't need "P" traps, you can use the "top hat" type in your shower. Can be cleaned easily from inside. All that digging never mind.

 

 

 

Septic vent pipe. Is this installed and does it go up high? at first mine was installed just up near the kitchen window, idiots, it now goes right up to the eves.

On 1/25/2024 at 6:05 PM, pj123 said:

no one understands the need to vent a drain

In fact knowledgable builders know what they are doing, but most cheap builders never care or even don't know that itraps or vent are needed. Good built condos or hotel do have both. In Japan there is no vent, but they chose pipes over size for ease of air movement. 
I did all plumbing for my house including vents and traps. I did all the plumbing from back of the house and under. No pipe in walls (I understand that won't be possible for all floor plans. Toilet tank head is 50cm higher than ground. 
Install traps under your house if it is possible and don't use smaller than 2" pipe if possible. 
 

I'm a crazy farang who don't know about plumbing when people look at vent pipes up to roof (they are out back of the house) 🤔😆😂

On 1/25/2024 at 12:05 PM, pj123 said:

I'm interested to hear from people who self build whether this is something they specified in their build.

Yes.

I’ve built an quite large bungalow type T-shaped house in 2008 The T is 20m by 22m and there are 5 wc’s.

I’ve have a vent on the 3000l septic and 1 11/2” went up to the roof  in each end of the 4” main tubing that connects from the toilets to the septic.

Normally no or very little smell in the bathrooms, but sometimes was very heavy smell when the wind comming from a special direction

Found out that the smell came from leaking connections between the toilet bowl and the 4” pipe in the floor, You can’t normally seal that from the outside as there is vent holes on the back side of covered bowls you can’t reach.

Checking in the building warehouses there are almost no hardware to do that seal. Only some rings of soft clay type to put there and lower the bowl and hope the clay will be pressed out and fill out the space airtight to the floor…….?

That is very difficult to lower the bowl straight down on the clay ring and not disturb or deform the ring.

 

Instead of reinstalling the 5 toilet bowls I put a small 60mm 12V type Pabst ball-bearing axial computer fan in one of the 2” end-vent tubes, that sucks air out of the tubings. These type of fans are really low cost and runs for years wit no problems.

I mounted it just with duct tape (Thaiwatsodu) and connected to an old 12V mains adapter. It draws only  0.7Watt

I then cut and restricted the 2” area to 1/2” in the other end of the toilet waste went, to keep a slight under-pressure in the system.

This totally and finally solved the smell problems from the toilets in all 5 bathrooms at the same time.

I then made the same trick to the vertical vent from where the drain and sink pipe go together to the concrete septic and put a 3” water lock to the pipe entering that septic (no2 after the black water septic from the toilets)

Thi also slowly sucked the smelling air out of the drain system and floor water locks (the thai ones on the picture in this thread dries out in a few hours)

 

Good luck with your other solutions, but these small fans really made it!

Post like these make the forum here invaluable. Thanks