Septic Tank

[Liquid Soul]

Recently we had our main septic tank emptied (2000 litres) for the first time after 14 months of use, now within three weeks it is full again?

Is this a common problem and has anyone experienced the same, if so what is the cause and what did you do?

Kind Regards

[Crossy]

How are you defining 'full'?

A septic will always be mainly full of water, the solids settle to the bottom and decompose leaving a sludge which needs removing occasionally, the liquids flow out into a drain-field or soakaway usually under your lawn (keeps it nice and green).

If you're getting overflowing then I suspect you've got a blocked drain-field (or no drain-field), time to get someone (not your builder) to have a look, could be a bad installation.

It's also possible your tank is too small, how many bathrooms / people is it serving?

Edited February 8, 2008 by Crossy

[Cuban]

Did they really empty it in the first place?

Has there been any change to the draining of the surounding area/your house? I wonder if run off rain water is now being directed into a feeder pipe to the tank?

[Liquid Soul]

How are you defining 'full'?

A septic will always be mainly full of water, the solids settle to the bottom and decompose leaving a sludge which needs removing occasionally, the liquids flow out into a drain-field or soakaway usually under your lawn (keeps it nice and green).

If you're getting overflowing then I suspect you've got a blocked drain-field (or no drain-field), time to get someone (not your builder) to have a look, could be a bad installation.

It's also possible your tank is too small, how many bathrooms / people is it serving?

Wow, thanks for your rapid response. Yes its full of water and backing up into the house. About 1 metre away from the tank there is I guess a drain field consisting of concrete rings I seem to remember.

And yes I believe that the tank is possibily too small, it serves the following

Two toilets

Two handsinks

One Urinal

Two floor drains

One double commercial wash sink

So yes I would say that it is too small, it just seems very strange that it lasted quite a while with no problems, then emptied of mainly solids now within three weeks we have a problem again?!

[Liquid Soul]

Did they really empty it in the first place?

Has there been any change to the draining of the surounding area/your house? I wonder if run off rain water is now being directed into a feeder pipe to the tank?

For sure Cuban they definately emptied it, I saw it myself, and got whacked for the payment to!

I cant think of any changes recently in the surrounding area and rain has certainly been minimal?

[Cuban]

Is the "soak away" allowing water to soak away?

[lopburi3]

As said - it appears to have a blocked drain (which was probably the reason you had to pump it the first time. There has to be an exit for gray water below your floor level from the septic or overflow tanks. You do not seem to have have gray water drains (if floor and sink go to septic tank) as most developments or city places would have. There has to either be a connection to such a drain system or pipes out into an area that can drain (not clay as we have here in Bangkok). Do you have a storm water drain of any kind?

[Crossy]

One double commercial wash sink

Has this got a grease trap? Greasy kitchen solids can cause issues with septics.

The fact that it's been ok although 14 months is a very short time for it to need emptying, suggests that something has gotten bunged up.

The drain-field usually consists of lots of perforated pipes laid under the ground as a soakaway although lots will depend upon how much space you have.

Useful stuff here http://www.bbc.co.uk/dna/h2g2/A873876 and here http://www.oasisenviro.co.uk/Septic%20Tank...20Operation.htm or try a Google on "septic tank size" for more info.

Edited February 8, 2008 by Crossy

[Liquid Soul]

One double commercial wash sink

Has this got a grease trap? Greasy kitchen solids can cause issues with septics.

The fact that it's been ok although 14 months is a very short time for it to need emptying, suggests that something has gotten bunged up.

The drain-field usually consists of lots of perforated pipes laid under the ground as a soakaway although lots will depend upon how much space you have.

Useful stuff here http://www.bbc.co.uk/dna/h2g2/A873876 and here http://www.oasisenviro.co.uk/Septic%20Tank...20Operation.htm or try a Google on "septic tank size" for more info.

Yes the sink does have a grease trap, which is emptied weekly.

The system consists of a grease trap, DOS 2000 lt poly tank, and behond that the builder dug a hole quite deep and filled it with concrete rings and then filled it with earth, Im not quite sure of the piping that runs to this though.

All water goes into the tanks from sinks, toilets, floor drains, we have storm guttering that sends the water into the garden quite a way from this.

[Beardog]

Your drainage field should be a minimum of 7 meters long 18" wide & a meter deep.We just put a 1&1/3 meter deep septic system with 100 cm. rings & I dug 5 meters of the 7 meters(won't do that again!) and we have zero problems- is your drainage field (soakaway)adequate? It is entirely possible your septic is to small for your needs. You should have many years before needing draining if you keep bleach out of your system. I was anal retentive when I laid in the septic & in hindsight I would have had a claw go down 2 meters(I had the crew dig the tank) & put in all the u-traps vent pipes & fittings & put them on the outside of the cement sidewalk for easy access along with a y trap for reaming out blockages. better to overbuild than underbuild by a longshot!

Hope you get it sorted out

Cheers

Edit

I am curious why your builder used a self contained dos unit & cement rings. Usually it is one or the other or is the cement rings the holding tank for the gray water , if so I hope he filled the surrounding area of the rings & not the inside of the cement rings.....nothing would surprise me in Thailand.

Logic isn't a taught skill here!

Edited February 8, 2008 by Beardog

[sweetchariot]

How often should you empty these? I moved into my house 18 months ago (new build), 2 of us live in the house (plus occassional guests), and not had mine emptied yet.

[Beardog]

How often should you empty these? I moved into my house 18 months ago (new build), 2 of us live in the house (plus occassional guests), and not had mine emptied yet.

Keep bleach & duck type cleaners-draino & don't overstuff with toilet paper & kotex type napkins & it should last years.

some posters have not emptied in 13 + years!

[Khonwan]

How often should you empty these? I moved into my house 18 months ago (new build), 2 of us live in the house (plus occassional guests), and not had mine emptied yet.

Even after 12 years of use (household of four, and frequent guests), my brick-lined soak-away (2m deep, ca.1.5m diameter) has never required emptying. Bleach is used infrequently, as is toilet paper. Other grey water simply discharges to a veg plot.

[JohnC]

For sure Cuban they definately emptied it, I saw it myself, and got whacked for the payment to!

A common scam here in Pattaya is to stick the hose in for 5 mins and show you a wet surface around the tank and then put the hose away and give you a bill, in effect they have barley pumped anything out. You say you saw them do it, did you look into the tank with a torch after they finished? did you check the tanker before and after to see if it had been filled? I know a number of people round here have been scammed by this as no one wants to look into a tank full of sewage! I had mine emptied after two years because of the smell but it has not really improved matters so now Im looking for a blocked drain!

[Beardog]

For sure Cuban they definately emptied it, I saw it myself, and got whacked for the payment to!

A common scam here in Pattaya is to stick the hose in for 5 mins and show you a wet surface around the tank and then put the hose away and give you a bill, in effect they have barley pumped anything out. You say you saw them do it, did you look into the tank with a torch after they finished? did you check the tanker before and after to see if it had been filled? I know a number of people round here have been scammed by this as no one wants to look into a tank full of sewage! I had mine emptied after two years because of the smell but it has not really improved matters so now Im looking for a blocked drain!

Got caught in the Pattaya scam when i lived there. They used the angle trick(measuring at an angle to give 2 more lines) fortunately our owner was out of town & we gave her the 2400 baht bill & later found out the government trucks are 300 baht.

And the septic (in the house still stunk to high hel_l) Guess they never heard of a U trap!

John more likely if it an older house or unless a fussy farang has been on this site or is a plumber by trade- they didn't know if you put a U trap ajoining the shower drain it keeps out odors along with a vent pipe.It pays to pay attn. to the words of wisdom on this site!!!!!!!!!!

[Crossy]

Im looking for a blocked drain!

We have a drain that blocks regularly which you are welcome to, buyer removes!

Back to our OP.

I'm no expert on septics, but this arrangement of concrete rings intrigues me. IF it is intended to be the soak-away/drain field I'll bet it's now saturated and simply can't handle the flow, some investigative digging inside the rings may be the next step, gonna need the wellies and gloves methinks

Possibly time to call in a contractor who knows what he's doing.

[Liquid Soul]

Your drainage field should be a minimum of 7 meters long 18" wide & a meter deep.We just put a 1&1/3 meter deep septic system with 100 cm. rings & I dug 5 meters of the 7 meters(won't do that again!) and we have zero problems- is your drainage field (soakaway)adequate? It is entirely possible your septic is to small for your needs. You should have many years before needing draining if you keep bleach out of your system. I was anal retentive when I laid in the septic & in hindsight I would have had a claw go down 2 meters(I had the crew dig the tank) & put in all the u-traps vent pipes & fittings & put them on the outside of the cement sidewalk for easy access along with a y trap for reaming out blockages. better to overbuild than underbuild by a longshot!

Hope you get it sorted out

Cheers

Edit

I am curious why your builder used a self contained dos unit & cement rings. Usually it is one or the other or is the cement rings the holding tank for the gray water , if so I hope he filled the surrounding area of the rings & not the inside of the cement rings.....nothing would surprise me in Thailand.

Logic isn't a taught skill here!

When the truck had arrived I checked the filler bars on the back and it was empty, not so when it left, and also I did stick my head in the tank (very suprised to find very little smells) and was definately empty, we stopped at the 2000 lt tank and didnt bother with the other two on the front of the house, the only way I felt scammed was my wife's cousin who said after we paid 5k plus, why didnt you use the goverment truck!! yeah thanks for that great insight.

It seems that the DOS tank receives all water from the main kitchen, two toilets and two sinks then has an outlet that drains into the concrete rings, 150cm wide and at least 4 metres deep, filled with earth, do I take it that this is very wrong?

Quote 'Possibly time to call in a contractor who knows what he's doing'

Um me thinks that these might not exsist here on Phangan, maybe its time to call a 'chang' of all trades!!

[Crossy]

If the rings are indeed full of earth then I suggest a little spade work will now show them to be full of "mud". Like I said, I'm no expert, but I would have thought that gravel would be the stuff to fill the rings with.

I reckon the only fix would be to dig a proper drain field (if you have space) or put in a new ring stack with gravel inside, as getting the whatever out of the old ring stack will be a thankless task

[Beardog]

I am indeed no expert on septics but consulted with a certified plumber from England & a farmer, so you know he knows shit don't flow uphill(without a pump LOL)Along with some of the expats on this forum that have either been through the school of hard knocks or did their homework. Seriously you need to ditch the ring setup. Either use the rings as the septic or the Dos tank as those rings are worthless as setup. The drainage field should be a minimum length of 7 meters & 18" wide by 1 meter deep. The way he has it setup is more akin to a closed system made to suck it out with a truck every month. I screwed up & dug 5 meters of the 7 before finding someone to dig the remaining 2 meters.

The approximate cost(might be higher or lower in your area )5500 baht a day to have a claw excavate a new drainage field.

The contractor you used brings a new meaning to the word "Schphinter Boy!

If you put in a real drainfield your system should be adequate. The way it is setup there is"no soak away whatsoever.Enclosed is what the MINIMUM field should look like & after you fill it with gravel-broken brick or clean smaller rocks cover it with visqueine plastic tarp material on the top & put about 3-4" of dirt on top of the plastic. The holes in the pipe(since drain tile is impossible to get is every 6-8" staggered 2" & laid to face down to drain the waste water.The setup should have a baffle in between the inlet & outlet also. Every site I looked at had a similar setup with the only inclusion....if space is not available make the drainfield deeper if shorter in length. The more the merrier cause no one wants to play the pump it out game !

Good luck

Edited February 9, 2008 by Beardog

[fremmel]

I've been doing a lot of looking on the internet about this because I'm getting ready to put in a system and from what I've gathered the septic tank connected to a seepage pit is an acceptable way of doing things if the land area isn't big enough to support a proper drainfield. Here's a link to the US EPA's version of a correct design for one. www.co.kern.ca.us/eh/pdfs/Land/TypicalSeepagePitDesign.pdf

But, as mentioned earlier, the seepage pit should be full of water, not "earth", so the water can leech out into the surrounding soil. I wonder if the DOS tank was installed backwards or is missing a part so that the solids from the tank are getting into the seepage pit and plugging it up.

Beardog, I hope your photos are not of your septic tank because it looks like they put the tees on wrong so that the scum layer won't be blocked. Here's a drawing from one of the sites Crossy referenced:

[Gary A]

We have a small septic system (concrete rings) that has been maintenance free for four years. The reason that we have no problem is because ONLY the toilet drains into it. The washing machine, shower and sinks drain into their own system. Bleach and some detergents kill the bacteria that makes a septic tank work.

[Beardog]

I've been doing a lot of looking on the internet about this because I'm getting ready to put in a system and from what I've gathered the septic tank connected to a seepage pit is an acceptable way of doing things if the land area isn't big enough to support a proper drainfield. Here's a link to the US EPA's version of a correct design for one. www.co.kern.ca.us/eh/pdfs/Land/TypicalSeepagePitDesign.pdf

But, as mentioned earlier, the seepage pit should be full of water, not "earth", so the water can leech out into the surrounding soil. I wonder if the DOS tank was installed backwards or is missing a part so that the solids from the tank are getting into the seepage pit and plugging it up.

Beardog, I hope your photos are not of your septic tank because it looks like they put the tees on wrong so that the scum layer won't be blocked. Here's a drawing from one of the sites Crossy referenced:

I am not sure of this system your photo is showing. I crosschecked 3 sites including google & this is the most recommended design.

Today we got pounded by Rain & the water table rose about 3 1/2 meters it did in fact fill the drainage field & immediately drain the minute the rain subsided. This design is one of 8 that I know of built in the Ban Sare & ban Ampur area. There are several different methods to use. The triple tank is popular but kind of redundant. This design is also on one of the earlier posts I forget when but I think it was 3-4 months ago. Mine works like it should & today was the big test & all solids remained in the bottom & the soak away did its job.

The most important element in everything I read is not the design but the drainage field as that is what dissipates the amount of light water. The downspouts direct the solids down & the inlet is open for reaming if needed. The baffle directs the solids downward.

We used this same design (except much bigger) in Portland Oregon in a commune of 64 people in 1974. We never had a problem. The drainage field was 11 meters by 2 meters deep & 1& 1/2 meters wide. Our sister commune ran even a bigger drain field for over 100-150 people in Loveland Colorado.

If you look at the cutout design of the Dos premade it is almost exact inlet goes in has a baffle in between outlet is slightly lower & the slope is 1-40 (1 ft for 40 ft. ) every different design the drainage field is still the main part that makes or breaks the system. The scum layer is supposed to be on the top portion of the septic allowing the heavy waste to settle to the bottom. The scum layer will naturally go to the top as it is not heavy. The baffle as in the premades are the same affect. The only thing different from the design we used 34 years ago was the added baffle my friend told me about. Even without the baffle the solids go downward & the scum layer being lighter floats to the surface & exits through the outlet tube & into the drain field. Many roads to the same path- the only constant is the minimum length of the drainage field.

I noticed your using a seepage pit design which is a totally different system from a basic septic design. I am sure that system would work also, but I am more familiar with the design I have used & do have enough room for the full drain field. You can always make a drain field deeper & wider using less length & be as effective. If you’re cramped for space the seepage pit design looks like it is the way to go. I hope you do not encounter the rock after 1 meter as I did! Even with a claw you would be ripping teeth off of it left & right.

Good luck on whatever design you go with.

Beardog

[koto]

Is the "soak away" allowing water to soak away?

Your PVC pipes are burried in cement, next time have pull through pipes, you could have a leak, like the tolet, you watch when they remove your waste and give them water, smile, find out what others pay, or put in tank # 2 watch your paper products, The life of the people is in the land.

Koto Keeper of the ocean

[Beardog]

I forgot to post the T's are pointing downward as in the photo that Crossy posted ,it is configured different as it is not a seepage pit design.It also is hard to make out but the baffle is at the same level as the inlet (blocking the scum layer as in the Photo & the outlet end is blocked on the receiving end forcing only the Light wastewater to be processed in the drain field. same same! Crossy design I am sure is great as he is knowledgeable in many fields. He has helped me before on several occasions in the electrical field! Thanks Crossy.

By the way welcome back again Koto!

Edited February 10, 2008 by Beardog

[fremmel]

The orientation of the tees is what I was talking about. The tops need to be higher than the outlet and the scum layer so it doesn't get out and plug up the drain field but it sounds like you took care of that. The rest of the system looks great. I really like that baffle idea from the roof tile. Most of the ring systems I've seen don't have a baffle but I wanted to put one in and wasn't sure how I could manage it easily.

[Beardog]

The orientation of the tees is what I was talking about. The tops need to be higher than the outlet and the scum layer so it doesn't get out and plug up the drain field but it sounds like you took care of that. The rest of the system looks great. I really like that baffle idea from the roof tile. Most of the ring systems I've seen don't have a baffle but I wanted to put one in and wasn't sure how I could manage it easily.

The original suggestion was to wedge wood across the same portion & enclose it with cement, but I had access to an arc welder & was a lot easier to put in roof tile & CHEAP + if it every needs replacing it is removable & for 40-50 baht a new tile slipped in.

I put a piece of #5 rebar 5/8" & welded studs on 3 points then drilled the tile to fit. real easy & simple. The rebar was 108 cm that was easily slipped in between the ring holes first one -pushed forward & then slipped back into the second opposing ring hole to balance the chunk of steel. The entire baffle system can be remade if it ever rusts out(probably in 40 years when I hit the pee stage)The toughest part was digging the pit(which I had 3 crews do) & the 5 meters I dug,before hiring a 62 year old man that whipped out the remaining 2 meters in 3 hrs- making me look a 115 year old fart! As Rimmer suggested in an earlier post.either hire a crew to dig your septic system or get an excavator & claw it out. knowing what a bear it was doing- I would have opted for THE CLAW & not increased my arms muscle mass & lost 3 & 1/2 kilo's

Cheers Beardog

Edited February 11, 2008 by Beardog