I have 2 septic tanks underground in my house..One has a round brass cap for emptying....

I cannot see any other cap...I guess somebody has covered it with cement..

My wife checked with the local government but they said that after 10 years all of the plans have been destroyed.

Does anybody know what I can do to find the hidden cap...I have the 'breather' pipe for this tank..

Are you sure the second tank is not just a bottomless concrete seeping tank?

5 minutes ago, CallumWK said:

Are you sure the second tank is not just a bottomless concrete seeping tank?

Thanks for your quick response...I do not know...Being English I know nothing about septic tanks...You are probably correct re the bottomless seepier....We have problems flushing the toilet but eventually ,after using a plunger it clears .This has been going on for a few months .

1 minute ago, p414 said:

Thanks for your quick response...I do not know...Being English I know nothing about septic tanks...You are probably correct re the bottomless seepier....We have problems flushing the toilet but eventually ,after using a plunger it clears .This has been going on for a few months .

How many breathing pipes you have?

2 minutes ago, CallumWK said:

How many breathing pipes you have?

I have one for the tank I can see..That covers the kitchen and main sink and main bathroom..There is another toilet in the second bathroom...That has the breather pipe for the hidden tank.

The seeping tank is connected to the septic tank, and never needs to be emptied, because it is an overflow tank and the water drains into the soil.

If you have 2 breather pipes in different locations, that would mean you have 2 septic tanks, because the pipe is to release gas build up.

Just follow the breather pipe, as the second tank maybe buried a little deeper.

5 minutes ago, p414 said:

I have one for the tank I can see..That covers the kitchen and main sink and main bathroom..There is another toilet in the second bathroom...That has the breather pipe for the hidden tank.

1 minute ago, CallumWK said:

The seeping tank is connected to the septic tank, and never needs to be emptied, because it is an overflow tank and the water drains into the soil.

If you have 2 breather pipes in different locations, that would mean you have 2 septic tanks, because the pipe is to release gas build up.

Just follow the breather pipe, as the second tank maybe buried a little deeper.

We had the septic tank emptied on Saturday.. The men told us we had the second tank which we did not know about. .They dug the ground by the breather pipe and also found a wide blue sewage pipe but could not see where it went..

It appears to pass into the garden of the house next door or otherwise underneath our house.

it goes across the back path of my house which is only about 0ne metre wide....

.the sewage pipe was app at one metre deep

4 minutes ago, p414 said:

We had the septic tank emptied on Saturday.. The men told us we had the second tank which we did not know about. .They dug the ground by the breather pipe and also found a wide blue sewage pipe but could not see where it went..

It appears to pass into the garden of the house next door or otherwise underneath our house.

it goes across the back path of my house which is only about 0ne metre wide....

.the sewage pipe was app at one metre deep

The sewage pipe probably would connect to a seeping tank. Or it is for the water from the sink/shower/bath.

My grey water doesn't go into the septic tank, only the toilets do, but go straight to the large drains around my land.

It would be rather dumb to burry a septic tank under the house, but we know where we are and i have seen it before, but in that case there was a brass cap in one of the bathroom floors

4 minutes ago, p414 said:

We had the septic tank emptied on Saturday.. The men told us we had the second tank which we did not know about. .They dug the ground by the breather pipe and also found a wide blue sewage pipe but could not see where it went..

It appears to pass into the garden of the house next door or otherwise underneath our house.

it goes across the back path of my house which is only about 0ne metre wide....

.the sewage pipe was app at one metre deep

4 minutes ago, p414 said:

We had the septic tank emptied on Saturday.. The men told us we had the second tank which we did not know about. .They dug the ground by the breather pipe and also found a wide blue sewage pipe but could not see where it went..

It appears to pass into the garden of the house next door or otherwise underneath our house.

it goes across the back path of my house which is only about 0ne metre wide....

.the sewage pipe was app at one metre deep

2 minutes ago, CallumWK said:

The sewage pipe probably would connect to a seeping tank. Or it is for the water from the sink/shower/bath.

My grey water doesn't go into the septic tank, only the toilets do, but go straight to the large drains around my land.

It would be rather dumb to burry a septic tank under the house, but we know where we are and i have seen it before, but in that case there was a brass cap in one of the bathroom floors

Thanks for all of your time and help, Callum,

The second bathroom seems as if it was added to the house as an afterthought. But it was done when the house was built.

I believe you are correct about the cap being under that bathroom floor,,, The house was built about 37 years ago.

I have wanted to change the small bathroom floor tiles...This will make me do it sooner.

There appears ,to me, to be nowhere else the cap could be considering where and how the large sewage pipe is.

Much appreciated for your assistance .

When and if I find this 'cap' I will inform you..

It may be some time as i have much to do .

Paul.

The sewage pipe and the breather pipe are two different pipes but in the same location, right?

A sewage pipe only has a function if it leads to a tank or drain. If it is blocked off at the outer end, it will have no function.

A breather pipe is only 1" and should not be too difficult to follow, once you know the direction it goes.

Breather pipe is connected to the septic tank, not to the seeping tank, and it may as well be blocked . So if no air can escape from the septic tank also nothing can get in.

As you say the house was built 37 years ago, I would be surprised the concept of septic tanks was understood then, or septic tanks were even available yet.

Good luck with it.

10 hours ago, p414 said:

We had the septic tank emptied on Saturday.. The men told us we had the second tank which we did not know about. .They dug the ground by the breather pipe and also found a wide blue sewage pipe but could not see where it went..

It appears to pass into the garden of the house next door or otherwise underneath our house.

it goes across the back path of my house which is only about 0ne metre wide....

.the sewage pipe was app at one metre deep

Septic tanks should never need to be emptied if maintained correctly. Mine hasn't been emptied since house built in 2009.

Before doing anything drastic you should get a 5kg bag of digester and flush it down the toilet then give it some time to get to work. The digester should break down the solids which then pass to the overflow tank and leach away. Unfortunately chemicals going down the toilet can destroy the process and may be need to be started over.

Metal detector?

16 hours ago, p414 said:

I have one for the tank I can see..That covers the kitchen and main sink and main bathroom..There is another toilet in the second bathroom...That has the breather pipe for the hidden tank.

16 hours ago, p414 said:

I have one for the tank I can see..That covers the kitchen and main sink and main bathroom..There is another toilet in the second bathroom...That has the breather pipe for the hidden tank.

I seriously doubts plans would be recorded.

Second, it isn't normal for waste from kitchen to be drain with a toilet if so there might be your problem.

Next, is your two bathrooms next to each other back to back?

If separate located for example other side of house there should be another vent and cap.

If together that is also a problem, the one not draining properly is full connected to the main one with cap when drained the second one isn't draining fast enough into the main giving the service guy the impression he is done.

if there is two tanks side by side with one cap it is connected by a simple blue PVC pipe to drain that isn't enough I had such a setup I ended up cutting a area into the title and inserting another cap I took a guess of location got lucky. This is common because having two caps mean double the cost to empty but having 2-1 can't empty both tanks reason my other toilet had a hard time draining as if it was cloaked.

On 4/9/2026 at 2:33 PM, thailand49 said:

I seriously doubts plans would be recorded.

Plans are recorded but depends where you live and for how long. We are out in the sticks near Chonburi and in 2009 had a bit of problem getting the plans passed. The sticking point was they seemed reluctant to accept that pumping the grey water tank out was not much different to a leach pipe.

The building inspector came out and when he saw where the water would go, was ok with it.

On 4/8/2026 at 4:20 PM, CallumWK said:

The sewage pipe and the breather pipe are two different pipes but in the same location, right?

A sewage pipe only has a function if it leads to a tank or drain. If it is blocked off at the outer end, it will have no function.

A breather pipe is only 1" and should not be too difficult to follow, once you know the direction it goes.

Breather pipe is connected to the septic tank, not to the seeping tank, and it may as well be blocked . So if no air can escape from the septic tank also nothing can get in.

As you say the house was built 37 years ago, I would be surprised the concept of septic tanks was understood then, or septic tanks were even available yet.

Good luck

On 4/8/2026 at 3:42 PM, CallumWK said:

The seeping tank is connected to the septic tank, and never needs to be emptied, because it is an overflow tank and the water drains into the soil.

If you have 2 breather pipes in different locations, that would mean you have 2 septic tanks, because the pipe is to release gas build up.

Just follow the breather pipe, as the second tank maybe buried a little deep.

Thanks Callum

On 4/9/2026 at 8:33 AM, thailand49 said:

I seriously doubts plans would be recorded.

Second, it isn't normal for waste from kitchen to be drain with a toilet if so there might be your problem.

Next, is your two bathrooms next to each other back to back?

If separate located for example other side of house there should be another vent and cap.

If together that is also a problem, the one not draining properly is full connected to the main one with cap when drained the second one isn't draining fast enough into the main giving the service guy the impression he is done.

if there is two tanks side by side with one cap it is connected by a simple blue PVC pipe to drain that isn't enough I had such a setup I ended up cutting a area into the title and inserting another cap I took a guess of location got lucky. This is common because having two caps mean double the cost to empty but having 2-1 can't empty both tanks reason my other toilet had a hard time draining as if it was cloaked.

Thanks for your input.

another way to try: open the septic tank, flush each toilet one by one, and check whether the wastewater from all toilets flows into that same septic tank. this will help you find out if your house has a second septic tank ...

Thanks to all for your input...The two tanks [?] are in separate locations.. The breather pipe for the lost tank is app 10 meters apart from the other one...The large blue drain pipe is pointing at a 45 degree from the septic tank with a cap...I will see if I can dig down where the tank cleaners have already dug the ground...They left soon after digging this hole [after throwing the stuff they dug out back in] saying they had another job to do..

There is little room to work where the breather pipe is..It is in the side walkway between my house and the wall between me and next door's house. this is only 4 feet across...Plus the shower part of the toilet juts out leaving a gap of only 18 inches before the wall..The breather pipe is on this wall.

Very small space for work ,which makes me believe that the cap is under this jutting out shower section...Thanks all for your help.

7 minutes ago, motdaeng said:

another way to try: open the septic tank, flush each toilet one by one, and check whether the wastewater from all toilets flows into that same septic tank. this will help you find out if your house has a second septic tank ...

tried that.....separate tanks...Thanks though,

On 4/9/2026 at 8:33 AM, thailand49 said:

I seriously doubts plans would be recorded.

Second, it isn't normal for waste from kitchen to be drain with a toilet if so there might be your problem.

Next, is your two bathrooms next to each other back to back?

If separate located for example other side of house there should be another vent and cap.

If together that is also a problem, the one not draining properly is full connected to the main one with cap when drained the second one isn't draining fast enough into the main giving the service guy the impression he is done.

if there is two tanks side by side with one cap it is connected by a simple blue PVC pipe to drain that isn't enough I had such a setup I ended up cutting a area into the title and inserting another cap I took a guess of location got lucky. This is common because having two caps mean double the cost to empty but having 2-1 can't empty both tanks reason my other toilet had a hard time draining as if it was cloaked.

My wife cheked with the district....They said they keep plans for just 10 years and then destroy them..

6 hours ago, p414 said:

My wife cheked with the district....They said they keep plans for just 10 years and then destroy them..

Personally, the plans aren't really necessary. Are you in a housing protected project or stand alone.

I'm a bit confused you or someone noted your kitchen waste is being dispose into the septic tank also?

As I noted is both your bathroom next to each other?

1 hour ago, thailand49 said:

Personally, the plans aren't really necessary. Are you in a housing protected project or stand alone.

I'm a bit confused you or someone noted your kitchen waste is being dispose into the septic tank also?

As I noted is both your bathroom next to each other?

1 hour ago, thailand49 said:

Personally, the plans aren't really necessary. Are you in a housing protected project or stand alone.

I'm a bit confused you or someone noted your kitchen waste is being dispose into the septic tank also?

As I noted is both your bathroom next to each other?

I was hoping that the plan would have shown if there were TWO caps

It is village with single houses, all on my Soi are single storey.......The bathrooms are .app 20 feet apart...There is a septic tank that the kitchen waste and bathroom at the back flows into. That is the one with a cap....The other bathroom has the toilet that flows into ???? ..via a large round blue pipe that runs into this bathroom. there is a breather pipe near each bathroom. My earlier posts detail what I and the workmen have found.

On 4/14/2026 at 6:13 AM, p414 said:

I was hoping that the plan would have shown if there were TWO caps

It is village with single houses, all on my Soi are single storey.......The bathrooms are .app 20 feet apart...There is a septic tank that the kitchen waste and bathroom at the back flows into. That is the one with a cap....The other bathroom has the toilet that flows into ???? ..via a large round blue pipe that runs into this bathroom. there is a breather pipe near each bathroom. My earlier posts detail what I and the workmen have found.

When you say " Village " is that a gated community basically houses within cookie cutter type all the same ?

I live in what is called a " Village " it is a large community but it isn't gated 99.9 are all Thai, there are nice homes then there are right next door across the Soi, tin can type houses LOL!

What surprises me whether in a gated community or village, the kitchen waste stuff is basically illegal as far as I know from my experience going into a septic tank which has to be drained regularly in which the normal <deleted> dump truck would refuse to do. These filled up 100 times faster that the septic. I think from your post this to be incorrect if it was the case your house outside area or even inside would really smell. How would I know my neighbor years ago did such a thing, she opened a small neighborhood restaurant, cook outsie like most Thais like to do the handyman came dug a hole in a area place a septic tank they build a cooking area, with a sink that lead to this septic, within a week the thing filled up with food all one has to do is go to a soi garbage can and stand next to one you would know what I'm talking about.

Most gated community even my house in the village, all around my house along the borders under are 6-8 incles cement pipes connect together at each corner they connect to a square cement drain box in the end, it all leads your kitchen stuff, shower, laundry, all drains into these pipes and lead out to the soi where there should be drains, these are the same drains that drain the rain water.

From you post the second bathroom cap must be covered since you noted a vent for that bathroom, the small vent pipe is usually connected to the septic tank. You can do it or call any handy person and have them take a look their building thinking come from the same school which is why they do things like this is anyone guess. I seriously be surprise if you kit he. Shower water is going into a septic tank.

Taking a chance after, I believe the septic tank is not too far from vent pipe, you will need to break up an area to find out a gamble but if you hit jackpot, it is easy to install a removal cap! Good luck!

On 4/16/2026 at 2:33 AM, thailand49 said:

When you say " Village " is that a gated community basically houses within cookie cutter type all the same ?

I live in what is called a " Village " it is a large community but it isn't gated 99.9 are all Thai, there are nice homes then there are right next door across the Soi, tin can type houses LOL!

What surprises me whether in a gated community or village, the kitchen waste stuff is basically illegal as far as I know from my experience going into a septic tank which has to be drained regularly in which the normal <deleted> dump truck would refuse to do. These filled up 100 times faster that the septic. I think from your post this to be incorrect if it was the case your house outside area or even inside would really smell. How would I know my neighbor years ago did such a thing, she opened a small neighborhood restaurant, cook outsie like most Thais like to do the handyman came dug a hole in a area place a septic tank they build a cooking area, with a sink that lead to this septic, within a week the thing filled up with food all one has to do is go to a soi garbage can and stand next to one you would know what I'm talking about.

Most gated community even my house in the village, all around my house along the borders under are 6-8 incles cement pipes connect together at each corner they connect to a square cement drain box in the end, it all leads your kitchen stuff, shower, laundry, all drains into these pipes and lead out to the soi where there should be drains, these are the same drains that drain the rain water.

From you post the second bathroom cap must be covered since you noted a vent for that bathroom, the small vent pipe is usually connected to the septic tank. You can do it or call any handy person and have them take a look their building thinking come from the same school which is why they do things like this is anyone guess. I seriously be surprise if you kit he. Shower water is going into a septic tank.

Taking a chance after, I believe the septic tank is not too far from vent pipe, you will need to break up an area to find out a gamble but if you hit jackpot, it is easy to install a removal cap! Good luck!

Thanks 49....A gated village and civilized, brick built houses with their own gardens .The sinks are with usual sink drainage. Not big enough for 'kitchen cooking waste'. No smells anywhere...'Bin man ' calls 2-3 times weekly..I will dig down soon to see where the breather pipe leads to..The cess men dug a bit but then had to'

go to another job'.../

4 hours ago, p414 said:

Thanks 49....A gated village and civilized, brick built houses with their own gardens .The sinks are with usual sink drainage. Not big enough for 'kitchen cooking waste'. No smells anywhere...'Bin man ' calls 2-3 times weekly..I will dig down soon to see where the breather pipe leads to..The cess men dug a bit but then had to'

go to another job'.../

Then all your kitchen, shower, should be going into city drains, have you ask others if in gated village someone should know!

Nevertheless, good luck.