We have a 'septic system' which is made up of 2 X 1100 liter tanks. The sludge accumulates in the first tank and liquid flows over to the second tank. Ultimately the water flows off to a massive leach field.

This week we had our system pumped out - just out of excessive precaution. No issues to speak of. It had been three years since the last time. Before the pumping I inserted a garden hose up stream (on one side of the house covering only the master bath) and I noted the water was flowing as expected. The people who did the cleaning thought everything was working fine and had no suggestions for improvements.

BUT - we recently needed to have a second story patio re-tiled. There is a drain which acts as a rainwater outlet. After the project - for the first time in 8 years we noticed a sewage smell. It seems that that drain had a dual purpose. Now that we have just had our two tanks cleaned there is still an odor on the new patio.

First simple question - is it normal for the 'aeration' tubes on any septic system to ALWAYS have odors ? If you say - yes - then I won't once again dig up my 3 ft deep tank to see if the water off the roof flows into the first septic tank. Otherwise I will and stick a hose in the roof tube as well as the 3 other bathrooms on that side of the house and see if the water hits the tank.

The aeration tube I have mentioned so far is built into the foot thick concrete wall of the house. At the other end of the system - at the far end of the leach field there is another aerator tube.

The 'mason' originally wanted to just close off the aeration tube and replace it with a 3 inch tube to let rainwater flow off the roof, but I was afraid that shutting off the tube might affect the septic system.

Thanks for any thoughts.

 

hi lhp -

You need one of the experts here, but I don’t think under any circumstances is rainwater diverted to a septic tank. Did someone misunderstand the current setup? If you think about it, why would you run rain water from a roof through a septic system? It would put an unnecessary load on the septic system and I think it is also a code violation. Instead I think you would just divert the roof water away from the house foundation.

But I may be mistaken – so you have to take the above with a grain of salt.

 

Any air pipe or tube or path into the septic system can allow odors to escape.

No roof water or rain water or patio runoff or sump pump discharge should run into a septic system.

Pumping the septic tank every three years is not unusual. A well established septic serivce company should be able to estimate when you need the tank pumped after asking you a few questions including about family size and habits.

The second septic tank here is an extra line of defense against grease (from the scum layer) and fine particulate matter (from the sludge layer) getting into the leach field where those materials will shorten the life of the field. The second tank or chamber should also be inspected periodically and any scum or sludge found inside pumped out. In some cases the second septic tank is equipped with a fan system and is an environment for a second group of bacteria, whihc does not thrive in the first septic tank to act on the effluent (liquid) and further reduce the effluent's hazardous characteristics..

After the pumping, no effluent leaves for the leach field until both tanks have regained the normal level of about 85% full.

You need to figure out where that vent pipe or drain pipe going through the 1 foot concrete wall ultimately leads to, and what water can get into it, and post back in order to kibitz us as to where to make our next suggestion.

 

Thank you.

We live in Mexico - but the house is very well built and probably 'some' of the construction principals used here probably are found at least on the west coast of the US.

We have been in this house going on 8 years now. The first 4-5 years here, every year, we got really bad odors in the master bath when the rains start (May). We had several 'knowledgeable' type people look at it. They were all wrong. Finally I started at the outside wall of the MB and dug out the PVC tube leading to the septic tanks. I got half way there and found that the really cheap PVC was crushed almost shut and whatever left the MB was feeding a massive avocado tree in our yard. Following that line along we found a 'register' which is kind of like a junction where several lines collect and then enter the first 1100 liter tank. That was fine but then we found that the 4-5" PVC tube connecting the 2 septic tanks no longer did so. So nothing ever did reach the second tank and therefore never did reach the bone dry leach field. So three years ago now we fixed all that. When we closed up the ground we slept well.

So just this month - out of an abundance of caution - I dug out the 3 ft deep dirt above the two septic tanks and had them both pumped out. Before the pumping I added water from the MB (virtually) and watched that the flow was correct all the way to exiting the second tank. I did not dig out all the way to the leach field. So that is our 'black' water system.

Then we have the 'grey' water system. I looked at the original plans for the house (1999) today. The info for the black water lines was not accurate - but I now know that. The grey water lines (showers, sinks, rainwater drains etc) wrap around the house and lead into the leach field (the same leach field) - which is required by our 'HOA'. I send the pool water over the back wall directly (there is a farm down there). When it rains here - it REALLY rains - kind of like out of the bible.

So it looks like the 'downspout' drain off our new patio deck leads into the grey water line on that side of the house. The guy who did the patio added a 4" tee at the drain and added a new 3" tube out onto the lawn beneath. I've never seen the drain going to the leach field back up, but at the time it made some sense to me to have the extra outlet as a precaution.

I never noticed odors on the 2nd story until after the patio project was complete. I tried capping (without glue) the newly introduced 3" drain tube - no difference. At the far end of the lot there is a perhaps 12' tall PVC tube which supposedly acts as an evap tube for the leach field. There were no odors there today. I stuck a garden hose in there today and let it run for a half hour or so. No backup - so I guess the tube is clear. I then did the same thing with the drain on the 2nd story patio - it did not back up - but I didn't check if the odor went away (to be honest).

So there are perhaps 4 or 5 different ways water can enter the grey water line. We are just two people (and 4 cats) and there are like 3 bathrooms which work but which we NEVER use. Maybe the 'stuff' in the grey water line is stale ?? I would really not like to dig up the grey water plumbing. In at least one area it goes under an outside stairway. I was thinking of maybe cutting a section of 4" PVC in half and trying to temporarily 'cap' the 2nd story downspout ...

Hopefully all my rambling makes some sense.

 

Showers and sinks are proper gray water that should go into the septic system and the septic system is supposed to be designed to take it. This gray water should go into the septic tank because going directly to the leach field will shorten the life of the leach field.

Rain water is not gray water

Nothing forbids the creation of a second leach field not connected to the septic system and if you construct this then nothing forbids putting rain water into it. It could be built in the same fashion as a French drain or a trench drain, some distance from the house foundation, and not subject to septic system standards. Being separate, if the second leach field backs up then it is not a septic failure.

If you constructed a second leach field and had a flush outlet at the far end (same as an aeration tube but did not protrude above ground) and it overflowed onto the ground and into the street once in awhile the chances are no one would notice.

 

lhp-

What did he tee into? I think I probably don’t understand but if this was a new patio up at the second floor, then didn’t a drain have to be added there from scratch? It sounds like there was already a vertical pipe in that location that led down to an underground drain system and the installer just connected the new drain to that drain pipe with a tee – and then connected the other side of that tee to a 3” drain pipe that routes the water onto the ground away from the house. Why would the water be routed in 2 directions from the patio?

Something doesn’t sound right there. Are you sure that pipe (are there 2?) at the patio drain doesn’t lead to the septic tank and is actually a vent pipe? You would get an odor from a vent pipe.

1100 liter septic tank seems small, but if there are two 1100 liter tanks that would give you close to 600 gallons. That seems a little small but maybe for 2 people it’s just fine. I’m no expert for sure.

 

Allanj - I think twice now you have used the phrase - "shorten the life of the leach field". I'm having some trouble fitting that into our world. Our leach field is a large hole in the ground. It is maybe 12-15 ft square and maybe 10 ft deep. It sits near the back wall of our property which is maybe 25' tall (the wall goes down). I'm a diver and the little I have looked into our leach field it looked like a cave. The roof of the 'tank' was cement but the walls/floor were just rocks/dirt (some wood) covered in grey dust. At that time there were no odors because for who knows how long the piping was broken. Given that description what is it that can be shortened ??

zoesdad - We have a ceramic tiled patio on the second story which we just re-tiled. Originally the 'mason' was going to install two lengths of new PVC out the 3 ft tall cement walls surrounding the patio but the walls were too thick and filled with rebar - so we looked at the existing drain. There have been times when there has been maybe 2-3" of water sitting on the old patio. Now that may have been because the old drain was not properly clear but I didn't see the harm in adding a new 3" tube out to the lawn. So one end of the tee goes to the tile floor, the other end goes out to the lawn and the third hole goes over the old existing tube which ties into the grey water line down below. I WAS worried that if we had simply capped the tube going into the grey water line we might have unforeseen problems in the future. I was worried that odors might some day go into the house.

Other than the occasional odors from a few years ago, we have never had a backup or any other problem inside the house.

Three years ago when we cut into the cement ceiling of the leach field it was bone dry. Now I understand why the black water wasn't getting there but the grey water pipes are big heavy 4-6" metal. While we did not trace them all the way to the leach field (ever) they looked pretty solid. Maybe there is another leach field for the grey water. If so it doesn't show up on any of the plans from 1999.

I went up onto the patio this morning and I couldn't find any odors. It did rain some last night and I did run the garden house into the grey water line in a couple places yesterday.

Worst case (I think) is I dig up the hole we put into the top of the leach field cap and check it out to see what makes its way there. I could call on a civil engineer for his opinion but it would cost me some and I'd like to be as informed as possible beforehand.

 

A large hole in the ground lined with unmortared bricks or blocks as chamber #3 in your system is known as a seepage pit in the U.S. In the past it was an acceptable substitute for a series of buried perforated pipes that looked like French drains and nowadays more common in the U.S. In the distant past said hole was sometimes the one and only chamber and called a cesspool. That is no longer legal in most parts of the U.S. When a cesspool or seepage pit failed back in the day, it was not unusual to just build another one next to it. When used for dissipating rain water it was called a dry well.

It is subject to the same shortening of life from fine particulate matter and grease and, in the case of laundry water entering it directly, lint and some detergent components impregnating the soil surrounding it. This prevents dissipation of the water into the ground and then the system backs up. If equipped with a vent pipe to the outside, it is still possible for odors to emerge.

 

lhp-

I think you may have something like my setup. I think that hole is called a “seepage pit”. I thought mine was a second septic tank following the first, but the pumper told me it was actually a “seepage pit”. The effluent is supposed to seep out through the pit walls. I have another gravel pit which follows the seepage pit, which I think apparently is for overflow from the seepage pit. But the gravel pit is always dry – and I guess that would make sense since if the seepage pit is working properly there would be no overflow.

I know when I had my house inspected I think the septic inspector misinterpreted the setup, because maybe that setup is not standard, and even he was confused. (He thought it was two septic tanks draining into a gravel pit).

It sounds like maybe you have something of the same thing. I think a leach field is larger and spread out with small pipes in the ground with holes for the effluent. At least I’m pretty sure that’s how leach fields are built.

Maybe that would mean that if your field is always dry that might not be telling you anything– because it is not a leach field. But if you are not having septic system backups then that would seem to indicate your system is working OK. That’s good! Well maybe the seepage pit scenario is something you could check into anyway.

If that pipe on your patio really connects to the septic system, then it seems to me you would expect odors. Why it never happened before does seem mysterious. If you have other vent pipes for the septic system then it seems to me that if you capped off that drain from the patio into the septic system, it shouldn’t hurt anything. You could try and run that way for a while and see what happens. You could use your hose test as you did before to test the system.

I don’t think capping that drain could cause a backup (maybe just new odors from someplace) – but I’m not 100% sure. Maybe one of the other guys here will weigh in on that.

 

Thank you both.

The project to find/dig up out septic system 3 years ago was long and stressful. The seepage pit part of it was at the very end and we were all ready to wrap things up. It took about a day to cut two holes into the concrete cap of the pit. One hole for a guy to climb into, the other to allow air for him to breath while he was down there. I do vaguely remember their removing stuff from the floor of the pit. Things like the wood which must have been used to build the cement cap etc 20 years ago. They did also take a pick to the walls and floor. I guess to rough the surface up some. I don't remember that part so well.

I'm the kind of person who changes the oil/filter in their car every 6 months regardless of how many miles have been driven.

 

lhp-

One other thing, if the patio drain is connected to the septic system I would think there would be a trap. I know an in-door floor drain to a sewer has a trap, so even though it isn’t normal (I think), for an exterior floor drain to be connected to a septic system, if it actually is connected to the septic system, then maybe the floor drain does in fact have a trap.

And if the trap dries out you would get a septic smell. So depending on the weather (when it last rained, heat, etc.) the trap may or may not be dry. Well ,it might be something to check.