Toilet goes to tank 1, through overflow underground pipe to tank 2 (which is overflowing and leaking). Underwound water is quiet high here, about 80 cm deep you are already in water which is part of the problem. How do I solve this without rebuilding complete septic system?

 

One of my ideas is making some basic leech field (but I couldn't find any hardware in Thailand, do they even do this here?). I was thinking buying 10 metres of blue pipe, drill holes in it, connect it to tank 2 and burry it. But I have zero experience.

 

 

These tank are basically just 2 concrete rings burry in a ground.

Without getting into replacing the entire system with a modern septic tank I would offer the following.
 

It is very possible to install a leech system here but will take a little extra work.

In Thailand, I have successfully installed both septic system leech fields and French drains for run-off water.

 

1. Research leech system design online and in English 

2. Research Gray Water recycling in the USA. If done properly, many systems are now fully approved. 
 

Use a combination of the above research and local conditions to design a safe, and effective system. 

 

3. Perforated pipe is generally not available in Thailand…I make my own by using an angle grinder to cut slots in the solid pipe. 
This is faster and easier than using a drill.

 

4. Drainage gravel should be 3/4” or larger with no fines. It should also have a layer of geo-textile cloth surrounding the gravel and pipe to prevent soil intrusion which reduces the air in the drainage system and thus reduces drainage and the aerobic bacterial action required to treat the leech water. 
 

5. A leech field can be located far away from the septic tank as long as the water can freely move within the pipe. 
 

There is more, but do some research and reply back after you get a basic design. 

Is it possible that the house is built on a mound of earth that was brought to the site and is not permeable enough?

 

There was the same problem with my GFs house.

 

The original setup looked very similar to your photo (including waterlogging).

 

Dug down about 1.5 metres to the permeable layer (then 10cms into that) installed 3 rings and the problem was solved.

 

 

We had the same problem....... tanks too deep and flooded when the heavy rains came......the builder broke into the  second tank halfway up and just ran a pipe to a roadside ditch!!!!!! That is now our leech field.

1 hour ago, AndyAndyAndy said:

to tank 2 (which is overflowing and leaking)

With respect, time to call in the septic tank emptying specialists. When I lived in Thailand, I had a local "lavender wagon" come and empty my septic tank - 100 baht per visit (pre-covid)!

 

33 minutes ago, Burma Bill said:

With respect, time to call in the septic tank emptying specialists. When I lived in Thailand, I had a local "lavender wagon" come and empty my septic tank - 100 baht per visit (pre-covid)!

 

Yes, we did that. Helped for a week before tank filled again and started leaking again.

57 minutes ago, Enoon said:

Is it possible that the house is built on a mound of earth that was brought to the site and is not permeable enough?

 

There was the same problem with my GFs house.

 

The original setup looked very similar to your photo (including waterlogging).

 

Dug down about 1.5 metres to the permeable layer (then 10cms into that) installed 3 rings and the problem was solved.

 

 

Yes, there is a is 80cm of normal soil and then I hit clay and ground water.

 

Because of ground water I can't dig any deeper.

52 minutes ago, Will B Good said:

We had the same problem....... tanks too deep and flooded when the heavy rains came......the builder broke into the  second tank halfway up and just ran a pipe to a roadside ditch!!!!!! That is now our leech field.

 

I have nowhere to run that water. I think I have to figure out some leach system as @Wanderer555 suggests or something.

Here in south Surin the standard practice is as Burma Bill suggests above: Order up the septic tank emptying truck. Sucks it out. All done in 10 minutes.

 

Depending on circumstances - size of tank & size of family - that might need doing every 6 or 9 months. But here in our main house with just 2 of us & a system that drains off the grey water to the khlong, we haven't had to use the visiting pump process even once since we moved in here 6.5 years ago.

 

 

2 hours ago, mfd101 said:

Here in south Surin the standard practice is as Burma Bill suggests above: Order up the septic tank emptying truck. Sucks it out. All done in 10 minutes.

 

Depending on circumstances - size of tank & size of family - that might need doing every 6 or 9 months. But here in our main house with just 2 of us & a system that drains off the grey water to the khlong, we haven't had to use the visiting pump process even once since we moved in here 6.5 years ago.

 

 

Yeah, like I said, I had it pumped out and it was overflowing again in less than a week.

Yesterday I dig a small hole next to it and it stopped overflowing. And water level is keeping under the ground level. 

So now I'm thinking maybe a install a third tank? Current pond is a 25% of what would new tank hold. Maybe not making tank too deep so it doesn't reach ground water. Just a single concrete ring (other tanks are 2 rings) and it could disperse not only downwards but also to the sides. 🤔🤔🤔 Current pond solves the issue, it just doesn't look/smell nice. It would definitely be cheaper and quicker than a leach field.

 

xxx

 

Not a solution, but some data for you to digest:-

 

The actual true water table will be lower than the 'pond'.  ie pond water is higher due to no earthen cover or weight bearing down.  As the wet season eases, the water table will drop and a pump-out should see you right until the next monsoon rains come.

 

Concrete rings allow the water table to rise from the base or joints whereas PVC septic tanks will only contain waste.  However, a PVC tank requires a 2nd 'semi-treated water' overflow tank which should ideally be full of holes to allow leeching (during dry season) or have leeching/evaporation pipes laid out under the garden.  3 rings deep for overflow/leeching tanks is my standard.

 

A rental house we occupied had similar problems during extremely wet periods and an overflow pipe was run to the soi by the local plumber