Septic Tank issue - advice needed please.

[cliveshep]

Our septic tank is as old as the house, maybe 20 years so not sure if style has changed. It's a Cotto-type plastic ball tank, with a netted barrier on one side where the overflow is (out to the street sewers here) and another division opposite with a pipe in it pointing up. Now as it is never less than half full or more of effluent it is not possible to do more than guess the internal arrangement - my sketch shows what I THINK happens on the inlet.

 

We needed to pump it out but with sickness in the family and other demands on money I had plundered my 400,000 to the tune of 70,000 baht so priority was to get that money back into the bank for the 2 months period prior to applying for the marriage extension so pumping it out along with a myriad of other things meant living hand-to-mouth for all of us while we scrimped on everything to build up the bank balance in time. We made it with 3 days to spare. 

 

The result was it was over-full and because the people here never clean the street sewers whenever it rains hard everything backs up the other flow from the flooded road outside. Not sure what effect that has apart from maybe washing out the bacteria? Anyway, we haven't pumped it out for 5 years of faultless working. BUT recently it started sucking out the trap on the upstairs en-suite toilet in our bedroom. That one is the furthest from the tank and before anyone asks there is no rodding eye in the system and the pipe is completely hidden across the kitchen ceiling void, down a duct and under a tiled path to join up the the other toilets. 

 

So as the toilet is flushed like always it clears with a gurgle, but then as it fills it clears again with another gurgle leaving the trap open. Topping it up with the bum spray and it promptly sucks it out again. So we got the lads in to suck out the tank, they didn't do too good a job going by what is floating on the top and after a day the trap sucking and 2nd gurgling has returned. My sketch shows pipes to the 4 toilets, the one bottom right goes via 3 x 90 deg bends to the upstairs toilet and has performed faultlessly for over 6 years since the en-suite bathroom and an additional ground floor bathroom were added.

 

I've asked She Who Must Be Obeyed to please call the tanker gang back again on Monday to stick their suction hose down the vertical pipe inside the tank whilst we flush mightily inside the house, and also take out some more effluent from the tank in general - to say she put up a fight is an understatement but to her it is one more thing going wrong in a year of problems of one sort and another and she gets mega-stressed and puts it on me. 

 

Has anyone got any other ideas other than my own which is a congestion of poo building up around the inlet inside the tank yet to be dislodged causing a build up inside the vertical pipe sections where flushing toilet water cannot clear into the tank? Both upstairs toilets lose their trap seals, not the ground floor ones.

 

[sometimewoodworker]

45 minutes ago, cliveshep said:

Both upstairs toilets lose their trap seals

It is because your toilets are not vented, look it up on the net and you will see exactly the problem and that your house waste water system is badly designed.

[userabcd]

In the septic tank, is that space and vent pipe on your diagram in the inlet side dry and is not blocked up?

 

The gurgling sound and suction indicates vent problems on the inlet pipes.

Edited March 26, 2022 by userabcd

[cliveshep]

57 minutes ago, sometimewoodworker said:

It is because your toilets are not vented, look it up on the net and you will see exactly the problem and that your house waste water system is badly designed.

I agree that on the face of it that would be the problem, but it worked well for over 6 years and in terms of the total pipe volume of air capable of being compressed I suspect that is why it never happened before normally. Also it has happened before but only when flood water from the outside street backed up into the tank that lies below street level. 

 

So would the tank outlet blocked be the likely culprit now?

 

I got drain rods and a plunger and I want to try and put some pressure down the vertical pipe to see if I can cause some dislodgement  tomorrow when it is light. 

[cliveshep]

4 minutes ago, userabcd said:

In the septic tank, is that space and vent pipe on your diagram in the inlet side dry and is not blocked up?

 

The gurgling sound and suction indicates vent problems on the inlet pipes.

Full of water to approximately effluent level but interestingly is goes up and down a bit when the toilets are flushed. I'm thinking tomorrow to get my drain rods and rubber plunger disc and pump it a few times to see if I can shake the blockage loose. As for the very correct point about vents, there is one vent but if it is still connected - who knows? So much work by my builders 6 1/2 years ago now anything could have happened.

[sometimewoodworker]

1 hour ago, cliveshep said:

I agree that on the face of it that would be the problem, but it worked well for over 6 years

No. Not on the face of it. It is the problem.
 

That it worked for 6 years is luck, not evidence of a design that should work. So trying to bodge a bad design so it doesn’t suck too much may work in the short term but may well introduce more problems.

The design of waste water systems, black and grey, is well documented and they should all be vented, the main reason is to avoid exactly the problem you are having.

 

That many village systems are badly designed but actually don’t suck the traps dry is often a function of a badly sealed concrete lid on the septic tank, that doesn’t make them well designed just that errors cancel 

[cliveshep]

Thanks for your input guys, all of which is of course correct. I was just hoping for something easier than trying to get at a completely hidden soil pipe to drill and fit a boss for a vent. TBH I only managed to do two things. One, got my drain-rod stuck with it's plunger under the bottom lip of the vent pipe because it is at an angle, once down the rod would not come back up (of course - hindsight) and 2nd totally enrage my wife who was making me pineapple pies and chicken pasties. That is now a non-starter of course - big sulks and silent angry wife!

 

That job has been abandoned as she is not in the mood because she wants to poke her nose in with all sorts of suggestions all prefaced by "I told you so" and then useless advice then stony silence after that produced the inevitable argument. So I had, as Bernard Cribbins song says - had an idea, a "sort of feeling", tied a thin braided line to the top of the bottom rod, unscrewed it, and pushed it down into the tank completely, feeding down the line. Then put a wire hook onto a piece of plastic water pipe, fished about, got hold of the line deep in sewage, drew it up and recovered one filthy drain rod. Washed up, discarded the line and told madam it was now out. Apparently I'm stupid, can't argue with that, I'm only a UK builder before and we are known for it. In my defence we never installed Cotto septic tanks either in my entire career.

 

My secret decision now is do nothing for the moment, to fit a vent on the vertical section entails a hole in the outside wall, drilling and installing a boss plus a bend or two and piece of pipe as a vent with a screen to stop wildlife getting in - it is something needing to be done but only as soon as madam is out of the house for the day so she cannot complain until after. 

 

I have NOT shared that plan! Sketch and layout of problem bathroom pipe with my proposed vent ;location , it being the only place I can get at it. The outside of the kitchen is in a tiled step along the covered way path and digging up the garden probably won't work.

 

I've got a big diamond saw to cut a hole in the outside wall plus a jack hammer and pretty much every other tool known to man so actually cutting the hole and cementing it back in after is not likely to present much of a problem. 

 

So what do you think - it'll work ok?

[4MyEgo]

24 minutes ago, cliveshep said:

got hold of the line deep in sewage, drew it up and recovered one filthy drain rod.

That's shi-t-y.

 

24 minutes ago, cliveshep said:

So what do you think - it'll work ok?

It will work.

 

Edited March 27, 2022 by 4MyEgo

[Encid]

17 hours ago, cliveshep said:

It's a Cotto-type plastic ball tank, with a netted barrier on one side where the overflow is (out to the street sewers here) and another division opposite with a pipe in it pointing up.

Rather than allowing your grey water to overflow to the street drains you could install your own grey water tank or soakaway.

That way flooded road drains will never back-flow into your septic tank and cause it to overflow.

Your grey water from the house (shower and sink outlets as well as washing machine drain) should be piped to your grey water tank, not your black water tank.

Have a look at my topic on septic tanks to see what I mean.

 

And yes I agree with STWW... your system needs to be properly vented at both the house wall where the black water exits and at the septic tank itself.

The vent outlets should be high (above human nose smelling height) and filled with mesh to stop birds and rodents from entering.

A lot of vents are installed under the eaves for these reasons.

Once painted the same colour as the house, you will never notice them again.

[sometimewoodworker]

25 minutes ago, Encid said:

And yes I agree with STWW... your system needs to be properly vented at both the house wall where the black water exits and at the septic tank itself.

If the soil stacks are correctly installed and vented then a vent at the septic tank is not required, it’s actually wrong, as the soil stack will vent the septic tank.

 

the proposed vent should really be at the bend not below it.
 

A vent at the septic tank will only be needed/useful  if you can’t correctly vent the soil stack

Edited March 27, 2022 by sometimewoodworker

[cliveshep]

Right then, today out with diamond saw, cut a square through the wall from outside, aided by the electric hammer, both machines rather large and heavy, found the soil pipe was within 10mm of the corner post on one side, 20mm from the back of the pipe duct on the back and about 15mm from the 50mm branch waste pipe from the shower and the 32mm pump main feeding the bathroom. So actually fitting the boss coupling with it's two 3-bolt ears totally impossible.

 

This calls for some Thai-style bodging thinks I.

 

Cut off the ears from the front half of the boss coupling with the mini grinder, and stuck on some 4mm dense self-adhesive foam strip 15mm wide around the hole, fished some doubled loops of iron tying wire around the soil pipe, applied a thick bead of acetoxy silicone around the cut-down coupling outside of the ring of foam, and slapped it on, fixing it above and below the boss with the tie wire twisted up tightly. Then added a 2nd loop of tie wire above and below to make sure, and built the hole back up with the rubble and 2:1 sand cement mortar (goes off like a rock in these temperatures), fitted a 500mm piece of 50mm pipe and bend pointing up and rendered it all in.

 

My wife shot upstairs, tested it - it's fine of course,  and helped clean up. Tarted up the render to remove any imperfections and sponged it all clean ready for painting tomorrow. She also cut and tied a piece of mosquito net over the top. It's all under a roof outside which is what dictated the position of the hole in the first place.

 

So to you guys who rightly pointed out my failings in not venting the soil pipe - thanks. Incidentally STWW - it is not a single stack SVP system by any means, somehow 4 toilets all get connected to one inlet on the septic tank but how the builders managed it is best not thought about, I do remember being despatched to buy a band-seal though so I can guess. The tank is vented though BTW as is or was the ground floor wc. Got a feeling I might need to fit a vent on the other existing upstairs bathroom in the same way as it does seem to pull a bit.

[Will B Good]

Can someone answer a couple of questions please?......don't want to start a thread.

 

I am pretty certain our bungalow has been plumbed without vent pipes.

 

However, there are three grey water and two black water tanks only metres away from the sinks and toilets..........

 

1. As the run to these tanks is very short, is venting not necessary?

 

2. The vents on the septic tanks themselves are just 1m high, 25mm plastic pipes.....is this going to cause proböems with bad smells......if so, can I just extend them upwards or even along the ground to the boundary?

 

Cheers

 

[sometimewoodworker]

10 hours ago, Will B Good said:

As the run to these tanks is very short, is venting not necessary?

The length of the run is irrelevant to a requirement to vent. The correct thing to do is to vent, however the vast majority of Thai systems are not vented, some work with no problem, some, like @cliveshep have a problem so the only correct answer is to vent every soil/ waste pipe that connects to a toilet or sink that has the problem.

 

10 hours ago, Will B Good said:

The vents on the septic tanks themselves are just 1m high, 25mm plastic pipes.....is this going to cause proböems with bad smells..

Time, and your nose, will tell ???? 

10 hours ago, Will B Good said:

can I just extend them upwards or even along the ground to the boundary?

I have done exactly that, before my nose got to find out ???? 

[sometimewoodworker]

11 hours ago, cliveshep said:

Incidentally STWW - it is not a single stack SVP system by any means, somehow 4 toilets all get connected to one inlet on the septic tank

I should have been more careful of my phrasing. I never thought that it was, as that would have been far too easy and joining multiple outlets nearer to the septic tank is a normal Thai “plumbing” practice. Few Thai “plumbers” understand the science of water and waste flow. The reason? Thailand is different ???? 55555555

[rwill]

As a temporary aid Homepro and other stores sell products to pour in the toilets that are supposed to help break down the waste.  I am not sure how effective they are though.  The same stuff is also sold as a soil conditioner at fertilizer stores.

Edited March 29, 2022 by rwill

[Dan O]

11 hours ago, Will B Good said:

Can someone answer a couple of questions please?......don't want to start a thread.

 

I am pretty certain our bungalow has been plumbed without vent pipes.

 

However, there are three grey water and two black water tanks only metres away from the sinks and toilets..........

 

1. As the run to these tanks is very short, is venting not necessary?

 

2. The vents on the septic tanks themselves are just 1m high, 25mm plastic pipes.....is this going to cause proböems with bad smells......if so, can I just extend them upwards or even along the ground to the boundary?

 

Cheers

 

Thai plumbing is typically unvented or vented as you described, also a poor installation. The short runs outside provide minimal venting to the tanks outside. The length of the rise or height isnt really important although you may have smells since it sounds like it's just open piping. They make a one way valve for this situation called a no-vent valve. It fits on top of the open pipe and allows air to flow into the pipe when the water flows by creating a vacuum, but closes to stop exiting air\smell from escaping when no water flow is present

[Crossy]

1 hour ago, sometimewoodworker said:

The reason? Thailand is different ???? 55555555

 

Yeah, Thai water flows uphill hence installing the shower drain at the high point!

 

Thai electric also not same-same farang electric, not need earth (this despite the label in Thai "this appliance must be earthed").

[Excel]

1 minute ago, Crossy said:

 

Yeah, Thai water flows uphill hence installing the shower drain at the high point!

 

Thai electric also not same-same farang electric, not need earth (this despite the label in Thai "this appliance must be earthed").

And even an educated explanation to them they don't believe either ???? Bit unfair really me saying that as decades of propaganda, poor if not deliberate lack of decent education and brain washing into not asking questions is the real root of them failing to understand.

[Will B Good]

3 hours ago, sometimewoodworker said:

The length of the run is irrelevant to a requirement to vent. The correct thing to do is to vent, however the vast majority of Thai systems are not vented, some work with no problem, some, like @cliveshep have a problem so the only correct answer is to vent every soil/ waste pipe that connects to a toilet or sink that has the problem.

 

Time, and your nose, will tell ???? 

I have done exactly that, before my nose got to find out ???? 

Thanks for that......great help.

 

Just been looking at AVV's have you ever used those?.......could they be a solution if things get sniffy?

 

My worry now is that all the pipework is boxed-in underneath the house and access would require drilling through the concrete........messy!!!

[Will B Good]

2 hours ago, Dan O said:

Thai plumbing is typically unvented or vented as you described, also a poor installation. The short runs outside provide minimal venting to the tanks outside. The length of the rise or height isnt really important although you may have smells since it sounds like it's just open piping. They make a one way valve for this situation called a no-vent valve. It fits on top of the open pipe and allows air to flow into the pipe when the water flows by creating a vacuum, but closes to stop exiting air\smell from escaping when no water flow is present

Thanks for that......will investigate....cheers.

[sometimewoodworker]

21 minutes ago, Will B Good said:

AVV

Avalon airport? 
Or https://avv.de/de/ ?
or A.V.V. https://zozo.jp/brand/avv/ ?

???? 

[sometimewoodworker]

@Will B Good be a proper Thai resident, do nothing until it becomes a problem, if everything is already fixed. ???? jai yen yen

[Will B Good]

8 minutes ago, sometimewoodworker said:

@Will B Good be a proper Thai resident, do nothing until it becomes a problem, if everything is already fixed. ???? jai yen yen

Kind of thinking along those lines already.......let's wait and see.......might get away with it....555

[Will B Good]

13 minutes ago, sometimewoodworker said:

Avalon airport? 
Or https://avv.de/de/ ?
or A.V.V. https://zozo.jp/brand/avv/ ?

???? 

Sorry......cheat valves or more correctly Air Admittance Valves. 

[userabcd]

14 hours ago, Will B Good said:

Can someone answer a couple of questions please?......don't want to start a thread.

 

I am pretty certain our bungalow has been plumbed without vent pipes.

 

However, there are three grey water and two black water tanks only metres away from the sinks and toilets..........

 

1. As the run to these tanks is very short, is venting not necessary?

 

2. The vents on the septic tanks themselves are just 1m high, 25mm plastic pipes.....is this going to cause proböems with bad smells......if so, can I just extend them upwards or even along the ground to the boundary?

 

Cheers

 

1) In all waste water systems it is good practice and necessary to vent.

 

eg.

 

 

2) Venting septic tank systems is also necessary to expel the buildup of harmful gases. There will be smells if the vent pipes are low and near the dwelling that is why oftentimes building regulations require a min distance between the dwelling and the septic tank location.

 

 

 

Edited March 30, 2022 by userabcd

[cliveshep]

AAV's more commonly referred to in my old homeland as Durgo valves.

 

Seen them in various sizes in Thai Watsadu for about 150 baht or so, and also the clamp-on boss couplings for 165 baht needing you to drill a hole in the soil pipe first and clamp these over - I suggest with a generous bead of silicone to seal as they don't fit that tightly. But if you can get at even a short piece of your pipe you can hole-drill a hole, bolt one of these in whatever size you choose and run the pipe out to somewhere convenient.

 

Logic says if the drain from the toilet is even below ground only a foot or so it should be enough to allow a vent to also go underground starting maybe only 150mm (6 inches) above it rune underground to a boundary or fence or wall to then run vertically without it filling with effluent. That might make is possible to vent most drains as contrary to Thai logic sewage does not normally flow uphill!

 

My solution to the problem works great, now only need to repaint a small bit of wall.

 

[sometimewoodworker]

14 minutes ago, Will B Good said:

Sorry......cheat valves or more correctly Air Admittance Valves. 

They are not all they are cracked up to be. Thy are mechanical and so some/many/all fail in time, for some that time is short. 
 

a vent pipe has no similar failure modes and if correctly installed will never fail.

[cliveshep]

In my picture is an old vent pipe - no valve, I believe it vents the old ground floor toilet and shower. My new vent I cut into the vertical drop from the en-suite bathroom above (it's a kitchen extension with bathroom above) has no valve, why waste money? When I was Project Manager on big multi-million new school or office builds the venting was by durgo valves simply for convenience and to avoid vent pipes appearing everywhere. They were most often low level, maybe 800mm off the floor and boxed in in a run of wc cubicles or canteen sinks. But where you can easily put the vent outside they are not required in my opinion.,

[userabcd]

19 minutes ago, cliveshep said:

In my picture is an old vent pipe - no valve, I believe it vents the old ground floor toilet and shower. My new vent I cut into the vertical drop from the en-suite bathroom above (it's a kitchen extension with bathroom above) has no valve, why waste money? When I was Project Manager on big multi-million new school or office builds the venting was by durgo valves simply for convenience and to avoid vent pipes appearing everywhere. They were most often low level, maybe 800mm off the floor and boxed in in a run of wc cubicles or canteen sinks. But where you can easily put the vent outside they are not required in my opinion.,

Those aav deal with the pressure in the pipe system, still need vents for the gases.

Edited March 30, 2022 by userabcd

[cliveshep]

Don't understand your point. The septic tank is already vented, one of the original bathrooms was vented, I re-did with all new sanitary ware and completely new floor and wall to ceiling porcelain tiling the two existing bathrooms, and built 2 new en-suite bathrooms, to one of two new bedrooms, and one from the Master bedroom, all when we remodelled the house. But we did not fit vents hence after 6 years suddenly we got problems now solved after a STWW timely reminder of our omissions. 

 

Another mistake now rectified was combining bathroom and kitchen wastes into one run in a 2 inch pipe out to the grey-water manhole instead of digging up the paving and running a new drain and manhole for it. Constant blockages attributed to Thai cooking/washing up styles, loads of fat and rice down the sink and I bit the bullet, we dug up and replaced all the drains previously in collapsing cement fibre pipes, and extended by 2 runs and 2 manholes right up to the kitchen and turned the 2 inch (50mm) waste pipes from kitchen and washing machine and 2 bathroom shower drains into the new manhole. 

 

Blockages now a thing of the past!