House Build Septic Tanks

[Negita43]

Can someone advise me?

I have read the previous thread on septic tanks but I am confused and have some questions:

What is a DOS tank – is it the large black tanks you can buy in builders merchants?

I have in the past installed a tank in the UK. It was a klargester and comprised 2 or 3 separate chambers.

The tanks I see in Thailand look nothing like this and to be honest they just look like a container for waste water that will eventually overflow into what I assume will be a soakaway connected to the outlet. (typically tanks like this are called cess pits and have to be pumped out frequently).

In the Thai tanks there seems to be no separate sections for sedimenting the solid waste and then allowing the liquid to overflow into a biological section where bacteria break down the waste further.

Do these Thai black tanks work or is there a better alternative available here.

Also is the system self sustaining or do you have to ‘feed’ them with ‘powder’ I see in some shops for these tanks.

My UK tank worked for 20 years and was emptied once and never needed ‘help’ in the form of added chemicals (although my local farmer neighbour did say that a dead sheep worked wonders for keeping septic tanks ‘healthy’ – I’m not sure if he was serious or if he had a dead sheep he wanted to get rid of!)

[passingas]

Coming from the son of a real, bonified, Union plumber....as long as at least two (read more than just one person, here) uses the facilities, then the excreted flora and fauna from each individual mixes and makes the bacteria get to work. But it takes at least two people using it to make it work. Sour milk, yogurt...anything with bacteria cultures will kick start the process. A dead sheep would really get bacteria going for sure...however I don't think I would go that route. The bacteria in a septic tank is anaerobic, they work in the absence of oxygen. You can get compartmentalized septic tanks here in LOS. I have two that the effluent from each one goes to secondary settling tanks and then the effluent from each of those goes into a tertiary, aereator tank that I keep an air pump connected to, to get aerobic bacteria to feast on anything else effluent-wise. This in turn is emptied out via a sump pump with a float switch. It works wonderfully here in the northern part of the country where clay substrate reigns supreme (hence all the rice farming). The reason I use two septic tanks is that one is a 1000 L for a single toilet and the second one is 1200 L for two toilets. I only run black water into these...not shower drainage or washing machine discharge. Those can go straight out to water whatever. When you purchase one of the black septic tanks, make them show you some literature or a cut-a-way version to make sure they are compartmentalized. pg

[passingas]

I forgot to mention....the 2 secondary settling tanks and the tertiary, aerator tanks are all made from the concrete rings, with the bottom one actually having bottoms to them. Do not let a Thai tell you it is okay to sink these anywhere near your well...they will try. PM me if you have additional questions....pg

[Negita43]

thanks where is LOS??

I don't have enough room for a very large instalation thats why I'm looking for a premade. Any names of suppliers/manufacturs.? I'm in Korat

[travelmann]

thanks where is LOS??

I don't have enough room for a very large instalation thats why I'm looking for a premade. Any names of suppliers/manufacturs.? I'm in Korat

Make your own with concrete rings about 120baht each, use 4 rings the bottom must be NOT OPEN as stated, paint inside with bitumen paint if it aint sealed its not a septic tank, join together with neat cement and overflow it into another with no bottom and the rings separated no cement. easy and cheap to do. Dont use bleach to clean toilets. MUCH cheaper than the plastic tanks.

Shower and sink water to the second open one, crap to the first sealed one. Plenty of sites will show you including coolhouse thai website

[passingas]

You can certainly make you own and it will be a lot cheaper, just remember to use two sanitation tees, the exiting one being about 5 to 10 cm lower than the main one coming in. These should be across from each other. Be sure to cut short pieces to fit on the top and the bottom of both tees. This allows for a scum layer to form and stay in the septic tank itself. If you just run straight pipes into it, the scum layer will not form and you will not have a properly working septic system. The part of the tee that is perpendicular to the rest of it is what you will attach to the incoming and outgoing pipes. The lower pieces need to be about 30 cm long on each. This will not impede the water/waste in or the effluent out. Water seeks its own level. The flush coming in will displace water that will exit and the solids will go to the bottom. The scum layer holds in the bacteria that will feed on all of these unused carbons. pg

[bbradsby]

When I was studying to be an architect, one summer I worked for a plumber doing construction. First day, Pappy the big boss (who looked exactly like Popeye) said plumbing's easy, all ya gotta know is <deleted> rolls downhill and payday's on friday! Thanks for the factual posts, PG! a pleasure to read good info on this Forum.

[mikecwm]

When I was studying to be an architect, one summer I worked for a plumber doing construction. First day, Pappy the big boss (who looked exactly like Popeye) said plumbing's easy, all ya gotta know is <deleted> rolls downhill and payday's on friday! Thanks for the factual posts, PG! a pleasure to read good info on this Forum.

He forgot the third rule - "never lick your fingers".

[canopy]

Realistically it is too much to ask for most people to make their own septic tank. People don't know how or why a septic tank works and there are too many things that can be done totally wrong because they just winged it. And then even a small leak will drain the entire tank and ruin its ability to treat waste. Unless you use very good and comprehensive specifications and have workers capable of following them to the letter, why take these risks? Right, so get a pre-made tank of the correct size, thickness, and multiple chambers. DOS and Cotto are brands that make some good tanks. Not only by size, they can be ordered in various thicknesses. They are more expensive than the run of the mill and so you usually won't see them laying about a building store, but stores typically have a brochure for ordering. Say no to the run of the mill tanks everyone else is buying unless you like your tank too be too small to effectively treat waste, too thin to prevent leakage, and just have one chamber. Cheap or good, that's the decision.

[BEVUP]

Hello All

Also from Korat, & just bought a house in a new Moo Baan

After reading this shall tell yu what the sales women said

First i did see one of the tanks from a distance that was to be installed (loked like one for every house ) it was just a black chamber

So when i asked the women how do I know when its full she said Quote - The toilets wont flush ( so the how long for the poo truck popped into mind)

I will have to check if there are at least some seepage holes in this to allow the water to leave or i may be calling the poo truck alot

Any thoughts to these Moo Baan tanks

[canopy]

Any thoughts you ask? Well yeah. Why don't you saw the entire bottom off completely. Great idea and it is amazing no one else thought of it. You are a genius. Please post pictures so the rest of us can have a good laugh because we read the instructions that come with the tank saying it is important to fill it with water all the way to the top immediately after installation.

[thaibeachlovers]

At the village house, I didn't see any outside tank top. I asked my wife and she says it all goes into a concrete tank under the floor. There are large brass screw caps in the floor that are apparently for the hose to go in when they suck the tank out.

[wayned]

If you look at the black tanks closer, They have and inlet on one side and an overflow on the other. If the system works correctly the sediment will settle and when the tank is full the liquid will over flow. It should drain into a leach field/tank, but most likely into the local klong through outside drains. If the system is working properly the black tank will fill and remain full and the only time you should have to pump it is when it becomes full of sludge. I have had my house in Bangkok for 16 years and it has never been pumped.

If plumbed properly the water from your sinks, washing machine and shower drain (gray water) do not go into the tank. They should drain into a leach field/tank, but most likly drain directly into the klong! You don't want this water draining into the tank as it will stop the natural decomposition process of the solid wastes.