I have a 700 l septic tank buried in my yard and I am getting curious as to when I should have the truck come to pump it out. It has been used by three people for 5 years and no noticeable problems. I originally added some special bacteria that I was tolds would eat the waste entering the tank, but I don't know if that is happening.

Septic tanks usually break down all solids and what is remaining is close to clean water that is then discharged into a soak pit, they shouldn't need emptying if they are working properly, changes in occupants can cause them to stop functioning properly though.

This tank is one of the round, black golf ball looking tanks. Are we talking about the same thing baz?

If installed properly and the overflow goes into a leach field or soak pit the tank should never have to be pumped out. My house in bangkok is 15 years old and the tank has never been pumped and I don't have ant drainage problems even after the flood of 2011.

OK, So maybe I don't have to pump out the tank. I have used a bacteria additive in the past by just pouring some down the drain of the shower and toilet and letting it do its job when it gets washed down into the tank, but the shop I got it from has closed. Are you familiar with this bacteria "additive"?

yes, a septic tank should look after its self till the point where the solids build up and tank is all solids.then the shit flows through to the field tile system. also make sure everyone understands how it works and does not use harmful chemicals that will kill the enzymes that do the work .

yes, a septic tank should look after its self till the point where the solids build up and tank is all solids.then the shit flows through to the field tile system. also make sure everyone understands how it works and does not use harmful chemicals that will kill the enzymes that do the work .

in a properly designed septic system the solids never built up but are broken down, diluted and flushed out. there's also no need to add any "additives" sold in shops nor is it mandatory to add a dead cat or sheep as it was suggested in several other septic tank threads.

important is to avoid (as mentioned above) harsh chemicals which destroy the bacteria, e.g. toilet cleaners which contain acid or flushing down matter which is not biodegradable.

in a properly designed septic system the solids never built up but are broken down, diluted and flushed out. there's also no need to add any "additives" sold in shops nor is it mandatory to add a dead cat or sheep as it was suggested in several other septic tank threads.

important is to avoid (as mentioned above) harsh chemicals which destroy the bacteria, e.g. toilet cleaners which contain acid or flushing down matter which is not biodegradable.

This makes sense. The question is if the builder included a leech field.

What happens if they did not?

It has been 5 years and average of two people using the system daily would have filled the tank by now ( I imagine there is a formula for this somewhere)?

I have not noticed any smell or overflow. I want to make sure that the bacteria are still active. Where can I buy the bacteria?

My dad was a plumber for 30 years and he always said that as long as at least 2 or more people....are using the system it will work from the different flora in our stomachs and he also said if you are in doubt, you can add a quart of milk or any dairy (think of the bacteria in yogurt) to it and it will kick start the system again. Do stay away from adding chlorine bleach or even pinesoil (popular bathroom cleaner/disinfectant) into the toilet. These will kill the bacteria. pg

Of course in a condo system one will never stop acid cleaner (vixol) or bleach use.

OP there is an inspection hatch. Waggle a stick in if you wish to feel the height of any solids.

Bear in mind the outflow may be halfway up and pointing downwards inside and must remain completely clear.

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Mr Naam nailed it. If you are not poring down copious amounts of bleach (duck etc.) your septic should never need any external bacterias added. They won't hut but the feces has all kinds of bacteria & the extra is really not necessary.

A good system with a proper drainage field should last 25-30 years(or more) if not killed by too much toilet paper Sanitary napkins & Bleach the # 1 septic system killer.