Septic Tank Soak Aways

[TBWG]

Hi

Have had a couple of these now for 4-5 years with no problems. However recently one filled up and was subsequently emptied. It has now filled up again mainly with shower water within the week.

Can anyone tell me how they are constructed and how the water runs away?. It appears to be made of several of those approx 1 meter diameter concrete drainage pipes with a round concrete slab on top with a small circular access lid with 2 holes for removal.

What I don't know is how the water seeps away does it have gravel in the bottom acting as a filter? or a series of pipes venting the water?

Any info appreciated

TBWG

Mod not sure of correct forum please move if appropriate

Edited November 8, 2007 by TBWG

[Farma]

The standard village septic tanks are a hole in the ground that has a number of concrete rings forming the hole. The rings may have holes in the sides to allow water to seep out. The bottom of the pit is dirt and that’s where the majority of the water naturally drains away from the pit into the ground. The ones I’ve seen being built don’t have gravel or pipes in the bottom.

The top of the septic tanks usually sits a few inches above ground level to prevent rain/flood water flowing into the tank when it rains.

As water seeps into the ground and away from the septic tank, the soil naturally filters the waste water. I’m also told toilet paper can clog the septic pits and prevent the water draining away. This maybe why your pit has refilled quickly.

A member of the health department has told me a well shouldn’t be dug within 30 metres of the septic pit.

Hope that helps.

Edited November 8, 2007 by Farma

[lopburi3]

If in town or city there should be a drain pipe near the top to take water out to gray water drainage system. If set by itself in country there should be perforreted pipes to drain it but not sure if they are used or not - probably they just poke some holes in side.

It sounds like the drain pipe is probably blocked - one method (not my recommendation) of clearing is to find the exit pipe (normally in a drain hole on street or next to house) and use pressurized air to blow back into septic tank (open top cover and place inverted 5 gal can with heavy worker on it) to lessen spray back.

If you have two holes on top perhaps one leads to the exit chamber and you would be able to use bamboo or something to clear it. But I would hire someone myself as could be rather unpleasant. The people who pumped you out last time might be able to fix the problem but there are a lot of cowboys involved in that business so best to use government workers when you can.

Four or five years is not very long and most people use plastic units these days. We had the type you mention and after 25 years the iron drain pipe rusted out and became blocked so had to have a new drain made but that should not have happened to you - unless the pipe was crushed by heavy truck running over it or something like that (had that happen in new home in US).

[jayenram]

In my experience, septic tanks are designed somewhat similar to the sketch below.

Two sealed tanks (with access points in the lid) 'separate' the liquids from the solids and allow the liquids to discharge into an excavated pit filled with gravel (the soakaway). This could alternatively be a trench. Eventually the two sealed tanks will require emptying.

However, in my limited experience in Thailand I've noticed that a high proportion of Thais in rural Thailand have a single cess pit which also acts as a very crude soakaway. A cess pit should be sealed and emptied when it becomes full. However, those here tend to be constructed of concrete rings on bare earth. The rings are neither sealed together nor are the lifting holes sealed so the water is able to 'seep' away. Again, a heavy build up of solids will eventually need 'removing'.

(Note: The outlets from the septic tanks should be slightly lower than the inlets to prevent 'back-up'. Also the pipes should be 'laid to falls' between the tanks and to the soakaway' As a rule of thumb for self cleaning velocity, 4" diameter pipes at 1:40; 6" diameter pipes at 1:60. All tanks should be vented from above water level to prevent build up of explosive gasses.)

Edited November 8, 2007 by jayenram
Note added

[TBWG]

Hi

Thanks for all the input, I fear that the only way to sort this is to do it the dirty way i.e dig it out and look

TBWG

[elkangorito]

If your septic system is "bottomless", I certainly hope that you don't get your drinking water from a nearby well.

Also, there is a product that can greatly reduce the "pump out" cycle of your septic system. It is called Actizyme & is available in Thailand. I met the Thai guy once, who sells it here in Thailand but I've lost his details. You can get his details by going to the following website & contacting them - ask them for his details.

http://www.southerncrosslaboratories.com.au/products.asp

I have used their products in commercial applications for many years in Australia. They are very effective.

[Lancashirelad]

Eventually the two sealed tanks will require emptying.

In reality, if the tank is working correctly, i.e. with the micro organisms breaking the solids down, tank 1 should hardly ever need emptying, if at all. Mine here in England hasn't been emptied for at least 15 years.

Tank 2 should do many years of a slow build up of more dense solids on the bottom.

NEVER use bleach in the toilet/sink if you have a septic tank. You will kill the bacteria and stop the tank working. Then it will need emptying.

[lopburi3]

Agree it should not need any more than what you normally put into it to work properly; as long as that is all you put into it. Our main unit has been pumped two times in 33 years and that was only to allow work - it has never become full. And that with five people using it.

[mobile69]

Also, there is a product that can greatly reduce the "pump out" cycle of your septic system. It is called Actizyme & is available in Thailand. I met the Thai guy once, who sells it here in Thailand but I've lost his details. You can get his details by going to the following website & contacting them - ask them for his details.

http://www.southerncrosslaboratories.com.au/products.asp

I have used their products in commercial applications for many years in Australia. They are very effective.

Makro sell a bottle of stuff called "Bio-Clean" for adding to septic tanks. About 180bt for a 1lt bottle. We had problems of full tank after too much bleach. The tank hasn't drained, but stays just below full.

[elkangorito]

My comments in blue.

Eventually the two sealed tanks will require emptying.

In reality, if the tank is working correctly, i.e. with the micro organisms breaking the solids down, tank 1 should hardly ever need emptying, if at all. Mine here in England hasn't been emptied for at least 15 years.

Actually, you are VERY lucky. Most septic systems need a pumpout avery 5 years or so. This "pumpout" frequency is dependant upon the size of the primary tank with respect to the size of the family (input), the food your family eats, the amount of "antibiotic" (& similar) medication your family takes, extraneous anti bacterial chemicals & the amount of liquid flowing into it.

Tank 2 should do many years of a slow build up of more dense solids on the bottom.

NEVER use bleach in the toilet/sink if you have a septic tank. You will kill the bacteria and stop the tank working. Then it will need emptying.

Exactly right!

Below is a link to a site that gives some pretty simple suggestions about septics. Also & I say again, I REALLY HOPE THAT NOBODY IS DRAWING DRINKING WATER FROM THE GROUND (a well) NEAR YOU (within 2km) IF YOUR PRIMARY TANKS ALLOW THE EFFLUENT TO SOAK AWAY DIRECTLY. BACTERIA CAN TRAVEL FOR A LONG WAY IN THE WATER TABLE & MANY PEOPLE CAN GET VERY SICK AS A RESULT.

http://www.health.sa.gov.au/PEHS/branches/...septic-tank.htm