Septic Tanks

[Greenside]

To keep closer to our budget we're electing to buy a bunch of the materials directly and among them are a 1200L septic tank and grease trap. The original Bill of Materials showed an figure of 12000 baht for the septic tank but on looking around I find them from about 4500 to 8900. The least expensive are branded Hero and sold by HomeMart and the priciest are made by DOS. They all look strong and of course there are no mechanics to worry about so what's the difference?

[bankruatsteve]

Since nobody replied, I'll give it a go... I think some of the containers are just that (ie: NOT septic) and you have to get the "purple trucks" to come by and suck out the shit ever so often. I've put in both the container things and what I think is a real septic system - but I don't really know for sure either. My suggestion would be to do whatever your neighbors are doing. At least you will all be in the same boat.

[craigt3365]

I'm no expert, but a true septic tank has a large leach field. Usually 10-15 meters long and about that wide. And they still need to be cleaned out every so often.

Here in our village, we all have a tank with a "grease trap" thingy and the overflow goes into the storm drains. It's basically a tank.

[egg]

you could make your own out of concrete and blocks ,,,,

capacity ,, about 3,000litres ,, split into 2/3 for the crap and 1/3 for the liquid to overflow and into the pipe ,,, naturaly, everything must flow with gravity

overflow ,, 90 metres of perferated PVC pipe(15cm ,, but not real sure) buried 40cm and laid on a gravel bed and gravel laid over the top(about 15cm)so soil doesn't block the holes,,,,,between the tank and the perferated PVC use normal PVC

someone will know a lot more about this setup than me ,, but it will work and probably not need emptying for years ,,, provided you dont put chemicals into the system

cheers

[Beardog]

We built ours using 150 cm 5 rings & a leech field that was 7 meters long X 60 cm wide (minimum is 50 cm wide) The leach field has to be 1 meter deep .Dos & the other brands didn't have a 90 degree hookup so We built our second septic so I could build in a straight run & avoid any bends a long the way. You can use busted porous blocks (the standard blocks- not q-con aerated style)for about 40 % of the leach field & the rest small gravel)Regardless of what tank you use home made or store bought the leech field needs to be these minimums . The best part of the system is it holds at least twice the amount of solids & is easy to work on 25-30 years later. If it is built right you will get 25-30 years easily without having to have a honey truck suck it up. The biggest problem in the septic builds in Thailand is that the contractors cheat to save a baht & the customer doesn't know what the dimensions are to build the leach field that & it is either built already when you buy or the customer is not around to make sure the field meets the minimums.The top of the leach field must have non porous material over the top of gravel to keep dirt out. The first septic I built would have lasted 25-30 years no problem till a tractor ran over the lid & I needed to replace the lid.

The second setup will handle 4-6 people no problem. PM me if you want the pics & diagrams on how to build this unit.

Edit: These are minimums for 750-1000 liter setups for 4-6 people using daily. More usage means more distance in the leech field -or another field joined side by side.

Edited March 17, 2011 by Beardog

[Greenside]

Thanks for the information everyone.

[jethro]

Good day guys. I have designed and supervised the construction of lot's of septic tanks here and in the U.K. . I use the meander type to my own specification, i try and keep it to nominal building material sizes, e.g. 8 feet x 4 feet ( 2.44 M x 1.22 M ) if one is going to use formwork with conc pour ,of course the size should be determined by the people in the dwelling. The pre formed plastic tank's Klargester arn't in the truest form a septic tank more a holding tank that needs to be cleaned out frequently. I make a longitudinal structure with a ratio of 3-1 i.e. 9 feet long by 3 feet wide with a dividing middle wall running along the length with a hole at the end not forgetting small vents along the top of this wall to let gasses pass through, the idea is for the faeces to enter at one end traveling down the length of the chamber slowing down en route then doing a 'U' turn at the other end and returning to the inlet end obviously on the other side ( outlet ) of the partition wall where by this time it should have settled nicely leaving a larger cleare zone for the effluent to go out into the drain field. What one has done is doubled the length of the laminar flow of the tank , resulting in the faeces staying in the tank and not going out into the drain field that would eventualy clog up ( this is why so many people have problems ) I have had tanks that have been used for years before need emptying BUT i monitor the depth of the sludge. hope this may help, regards Jethro.

nkruatsteve' timestamp='1300278688' post='4287038']

Since nobody replied, I'll give it a go... I think some of the containers are just that (ie: NOT septic) and you have to get the "purple trucks" to come by and suck out the shit ever so often. I've put in both the container things and what I think is a real septic system - but I don't really know for sure either. My suggestion would be to do whatever your neighbors are doing. At least you will all be in the same boat.

[BuckarooBanzai]

We installed one of the big black plastic tanks and put in a small drain field. Only used for sewage and not gray water. The reason I mention this is that two days ago we had it pumped out for the first time. Ten years of service no problems but the toilet just recently started to drain slower than usual. The tank was full but after 10 years who can blame it.

[katabeachbum]

We installed one of the big black plastic tanks and put in a small drain field. Only used for sewage and not gray water. The reason I mention this is that two days ago we had it pumped out for the first time. Ten years of service no problems but the toilet just recently started to drain slower than usual. The tank was full but after 10 years who can blame it.

these tanks are very simple design, and only 2 things matter.

Quality of plastic used

Size

I have seen to many house plans with tiny tanks. Increasing size provides hazzelfree ownership for decades.

Sorry to say, OPs 1200 liter is a joke, even with only one toilet and no paper used, it is likely to need to be sucked empty in 6 months. Not to mention the impact on environment a small tank provides

[jethro]

Hi, B.B. you don't say how big is big, but this is my point if you don't clean out these klargesters ( and proper septic tanks )from time to time this is what happens the drain field pipe and the field get's blocked, and i am very surprised indeed that it really lasted 10 years before emptying but of course i don't know how much and how many times it was used ? it really isn't that difficult once in a 'blue' moon to just check the sludge level, and trust me please it's a lot cheaper to have it pumped out than to start a new drain field,and had you done this you wouldn't be incurring your problems now !!!! so for all you who are loking for advice here :- don't think your being clever by not having the tank pumped out,cheers Jethro [ quote name=BuckarooBanzai' timestamp='1304410576' post='4398391]

We installed one of the big black plastic tanks and put in a small drain field. Only used for sewage and not gray water. The reason I mention this is that two days ago we had it pumped out for the first time. Ten years of service no problems but the toilet just recently started to drain slower than usual. The tank was full but after 10 years who can blame it.

Edited May 3, 2011 by jethro

[BuckarooBanzai]

Hi, B.B. you don't say how big is big, but this is my point if you don't clean out these klargesters ( and proper septic tanks )from time to time this is what happens the drain field pipe and the field get's blocked, and i am very surprised indeed that it really lasted 10 years before emptying but of course i don't know how much and how many times it was used ? it really isn't that difficult once in a 'blue' moon to just check the sludge level, and trust me please it's a lot cheaper to have it pumped out than to start a new drain field,and had you done this you wouldn't be incurring your problems now !!!! so for all you who are loking for advice here :- don't think your being clever by not having the tank pumped out,cheers Jethro

Sorry I don't know the size but probably big enough to fit 3 people in although I certainly would not recommended it. I believe a proper septic tank, which has multiple chambers, protects you from some of the concerns you mention. The sludge stays on the inlet side, if full it is pumped out and everything works as new. This is not true of the cement style holding tanks used by so many of the locals which would be a cause of concern for drain fields. As for how many times it has been used I will start a new spreadsheet and get back with you in 6 months.

[jethro]

Hi B.B. were both on the same wave length here as i too agree that these local concrete caison rings they use to form a sewerage system works to a fashion but could be improved upon. Very simply put to anybody not in the know is that the more settling that occurs within the septic tank the better and that's where my simple longitudinal meander tank helps imensly. It's so simple to construct and not expensive, infact i have had 2 No. constructed on my friends build here in Thailand. If anyone would like any info on this or other matters pertaining to construction they only have to ask, regards Jethro

Hi B.B. you don't say how big is big, but this is my point if you don't clean out these klargesters ( and proper septic tanks )from time to time this is what happens the drain field pipe and the field get's blocked, and i am very surprised indeed that it really lasted 10 years before emptying but of course i don't know how much and how many times it was used ? it really isn't that difficult once in a 'blue' moon to just check the sludge level, and trust me please it's a lot cheaper to have it pumped out than to start a new drain field,and had you done this you wouldn't be incurring your problems now !!!! so for all you who are loking for advice here :- don't think your being clever by not having the tank pumped out,cheers Jethro

Sorry I don't know the size but probably big enough to fit 3 people in although I certainly would not recommended it. I believe a proper septic tank, which has multiple chambers, protects you from some of the concerns you mention. The sludge stays on the inlet side, if full it is pumped out and everything works as new. This is not true of the cement style holding tanks used by so many of the locals which would be a cause of concern for drain fields. As for how many times it has been used I will start a new spreadsheet and get back with you in 6 months.

[jethro]

Good day guys. I have designed and supervised the construction of lot's of septic tanks here and in the U.K. . I use the meander type to my own specification ,of course the size should be determined by the people in the dwelling. The pre formed plastic tank's Klargester arn't in the truest form a septic tank more a holding tank that needs to be cleaned out frequently. I make a longitudinal structure with a ratio of 3-1 i.e. 9 feet long by 3 feet wide with a dividing middle wall running along the length with a hole at the end not forgetting small vents along the top of this wall to let gasses pass through, the idea is for the faeces to enter at one end traveling down the length of the chamber slowing down en route then doing a 'U' turn at the other end and returning to the inlet end obviously on the other side ( outlet ) of the partition wall where by this time it should have settled nicely leaving a larger clearer zone for the effluent to go out into the drain field. What one has done is doubled the length of the laminar flow of the tank , resulting in the faeces staying in the tank and not going out into the drain field that would eventualy clog up ( this is why so many people have problems ) I have had tanks that have been used for years before need emptying BUT i monitor the depth of the sludge. hope this may help, regards Jethro.

nkruatsteve' timestamp='1300278688' post='4287038']

Since nobody replied, I'll give it a go... I think some of the containers are just that (ie: NOT septic) and you have to get the "purple trucks" to come by and suck out the shit ever so often. I've put in both the container things and what I think is a real septic system - but I don't really know for sure either. My suggestion would be to do whatever your neighbors are doing. At least you will all be in the same boat.

[extexthai]

Okay, here's my two Bahts worth....I would hope some of the better premade, plastic septic tanks are chambered....TIT....and most have a media of sorts in the large chamber. Usually plastic, geometric, sphere shaped thingys. This aids in the anerobic microbes (without oxygen), breakdown of the solids. The liquid effluent flows on out, so there fore needs to be sloped. No one seems to know about the scum layer that forms between the settled solids and the clearer liquid effluent that lies on top. This scum layer is important. To achieves this, one needs to have a baffle in their set up. If you chose to go with the concrete rings, use two sanitary tees on the input and output (this being a bit lower than the input for drainings sake) inside the tank area. Glue in extension pieces on the bottom ends (50 cm or so for both) and leave the top ends open. This makes for your scum layer, a place to sit, while the lighter liquid effluent raises to the top and flows out the output side.

I could not put in a leach (drain) field....hard pan clay substrate (think rice farming area), so I put in an additional settling tank and then an aerator tank that I aerate continually. This promotes aerobic (with oxygen) microbe action to eat the "bugs" (not necessarily insects...undesirable effluent particles) and then it is automatically pumped out via a sump pump with a float switch, into the garden are. Before adding the aerator pump, the effluent coming into that last tank was black and very odiferous. After about a day and a half, the smell was gone and the effluent was a lighter, mocha color. This is okay for watering with, but obviously...not to drink. Happy plumbing....ett