Septic System Questions

Old 12-09-16, 09:26 AM
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Septic System Questions

We have a septic system and we are getting odors in the master bath. We live in Mexico but the house is only 20 years old. I have the 'blue-prints' for the septic system from the original architect. They show lines for 'clean' water and 'black' water. They also show 'registers' for both lines. The only thing above ground (the only thing we see) is a long 3" PVC pipe at the farthest point of the lot.

Can anyone help me understand this system ? Do septic systems in the US also have registers ? Do the registers need to be maintained over time ? Should we be putting something into our system to facilitate the process/maintain the system ?

Old 12-09-16, 09:53 AM
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I can't really help with explaining your septic system. There are many different types of systems even here in the US and I've not heard the term register used as a component of a system.

However, odors in the bath should not occur regardless of system type. If the system is not backing up, odors may indicate a bad seal on the toilet, or a problem with plumbing drains or vents that result in sink or shower traps not holding water and preventing escape of sewer gas.

If your septic system has tanks (common in US), they generally need to be pumped out as part of normal maintenance. Usually the recommendation is they be pumped out every few years although under ideal conditions much longer intervals are possible. I suggest you get an inspection from a septic service company; they will explain your system and tell you if you have tanks and if they need to be pumped. There are other maintenance tasks that apply to some types of systems, such as cleaning filters. Generally no chemicals or such are required in a properly operating system.

If inspection of your septic system finds all is well, then I would start with examining around the toilet in the bath to see if there are any signs of leakage around the base, which would indicate a failed seal.
Old 12-09-16, 10:58 PM
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In Central and South America I've usually seen cesspits and not true septic systems. Does your documentation show a septic tank and separate leach lines? How large is your lot?

But, back to your smell. Like CarbieTipped mentioned, it's likely it's something simple like the seal under the toilet that is leaking. It might not be leaking poo juice but there might be a slight gap allowing sewer gas to enter the home. Usually it's cheapest and easiest to "pull"/un-install the toilet and re-install it and that takes care of the problem. It's only a few dollars in parts and about an hour's labor.
Old 12-10-16, 03:14 AM
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The bathroom with the odors - which are not always there by the way (but seems strongest after a heavy rain) - has a toilet, a large tub and a shower. There are two conical drains in the floor and I have inserted radiator like 1" hose into each drain to ensure they drop into the water below. I could certainly put a new seal under the toilet but I don't know what I could do about the tub.

The 'tank' itself has nothing exposed except a PVC vent at the far end of the lot which stands perhaps 10' tall. earlier this year I put a cap on the tube because I thought it was getting filled with rainwater and this not allowing venting - that made no difference. The septic tank (from the schematic) consists of 3 stone walled chambers - a) a collection area b) a fermentation are and c) an oxidation chamber. There is supposed to be an outlet on the oxidation chamber for the 'clean' water, but if there is it would be about 4 ft down a tall wall - and I don't see it. At the far end of the lot - near the PVC vent is a cement slab with a large propane tank on top. That would make it pretty hard to open up the 'oxidation' chamber if that were required.

It looks like the toilets (black water) have separate lines for the sinks/showers (clean water) coming out of the house and heading for the septic area.

This is the first house we have ever had with a septic system - I only have the simplest of understanding of what is involved. One concern I have is we planted a couple fruit trees in the yard a few years ago and they might be over the septic. I remember when we dug the hole for one tree there was some man-made earthen tile that I hit.

In the past someone had mentioned putting something down the drains to speed the fermentation process.
Old 12-10-16, 03:23 AM
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You don't want trees planted over the drain lines! The roots will seek out and plug the lines
Adding yeast to the system will help energize the bacteria that eats the solids in the tank. There are also commercially prepared products you can buy but I'm not convinced they are any better .... and they cost more.
Old 12-10-16, 05:12 PM
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The solid matter will settle and decompose where it lands first, namely in the first tank (collection tank). Some will find its way to the second tank and a small fraction of that will find its way to the third tank (oxidation tank) as liquid overflows from one tank to the next. In the U.S. an oxidation tank is usually equipped with a mechanical aerator not too much different from a fish tank aerator (except larger).

The solids do not decompose to liquid completely so the tank needs to be pumped out periodically. Of course the first tank will fill up first.

A real septic tank system has only one final outlet , namely the drain field (leach field) or sometimes a drywell (another tank called a seepage pit that is porous). If the "septic tank(s)" is/are not sealed and liquid can seep into the ground directly under them then solids will still decompose inside them. The disadvantage is that the liquid that ends up in the soil is more toxic compared with the liquid coming out of the final outlet of a sealed septic tank system.

Last edited by AllanJ; 12-10-16 at 05:51 PM.

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