Earlier this week we had the blue pump truck empty our septic tank. The employee told us that we needed more air pressure to have a smooth functioning. At present the septic tank has one 1 inch 4 m long air pipe.. I know that back home we would vent the entire water system from the roof. This is a 3-4 concrete ring tank encased in the house concrete slab..
The water 3/4 inch blue pvc pipe main runs from the street and goes all around the house in the open drain channel serving 2 bathrooms and multiple taps. ( see drawing ). For the bathrooms, the pipe goes into the concrete slab and then up in the wall and across the bathroom back wall to feed the 4 elements ( bidet, toilet, basin, shower ).

In order to add more air pressure i was thinking of adding pipe rising vertically from the water entrance at each bathroom. SEE the X on schema.
I am not quite sure it would work since i would be coming at the lowest point of the system.

Another option might be to drill the concrete covering the tank and add another vent pipe..

Any suggestions, comments, looking for your expertise.
Thanks all. Appreciated.

the-monk wrote: ↑

August 4, 2018, 6:31 pm

Earlier this week we had the blue pump truck empty our ##### tank. The employee told us that we needed more air pressure to have a smooth functioning.

Is it working OK now?

If not what problems are you experiencing?

If you aren't having any problems then don't fix them.

What you are reporting seems like they are taking utter BS to me.

Why would you listen to an uneducated employee. I have asked our poo man(the owner) about some issues with our system and he doesn't know ####, excuse the pun.

Can anyone shed any light on why this blog site doesn't like the word S-E-P-T-I-C and shows it as ###### instead? Mods?

Agree entirely with the two earlier respondents - if it ain't broke, don't fix it. By the way, this is the correct way to construct a se-pt-ic system. The inlet (right) is obviously higher than than the outflow (left) which goes out in a slotted 10 cm pipe to a 10 metre 60 x 60 cm absorption trench filled with crushed aggregate and sand. With this arrangement a crust forms over the top of the effluent water which isn't disturbed by water flow either in or out. In your situation, if what you have is working OK, that is great. In planning, if two flushing toilets are connected to the same inlet pipe to the tank, a breather pipe should be fitted between the two so the suction created by flushing one doesn't suck the water out of the other pedestal, allowing foul gas to rise through the empty pedestal.

Is it just me , or am i missing something , the diagram shown, is venting a 3/4 inch water pipe (why ?) , it is not about venting the methane gases out of the s-e-p-t-i-c tank ,,,maybe i'm just gettin to owd fer this ,

There seem to be a few misunderstandings going on in this thread.

First when you vent the waste water system you are not directly venting the se-pt-ic tank.
Venting the waste water system is designed to stop the water in the traps being siphon out., it functions with a S.E.P.I.C.T. tank, mains sewer system, or cesspit.

So with an unvented system you have a really good chance of your "P" and "S" traps continuously being siphoned dry whenever you flush a toilet (assuming a combined waste water system) or alternatively when you empty the sink (with a grey water/ black water separation).

That is the reason for venting your house plumbing and why a ½" or 1" pipe isn't going to be anywhere near big enough to vent a 4“ toilet waste pipe, it just can't allow enough air in fast enough to stop the siphon action.

Then we come on to venting the S.E.P.I.C.T. tank there we have a completely different requirement. If your house plumbing is properly vented then the waste water and solids suspend in it or pushed by it will not be filling the pipe, they will be flowing along the bottom with air above them. A S.E.P.I.C.T. tank with no venting will not stop this flow as the displaced air (and any gas generated in the S.E.P.I.C.T. tank) can flow in the opposite direction to the waste flow and exit through the house venting (a good reason for the house vent to be above the roof)

So if you have a vented house system no S.E.P.I.C.T. tank vent should be/is needed.

If you haven't got a vented house then the S.E.P.I.C.T. tank needs a small vent to stop a build up of gasses bubbling up out of your toilets ½" pipe will almost certainly be big enough (unless you have a 100,000 litre tank and the required solids to fill it ). You also are lucky that your waste plumbing is working.

Which ever system you have Pressure (positive or negative) in the system is exactly what you do not want, ambient air pressure is needed.

[ sarcasm ]Though of course TIT and everyone knows that Thai waste (like Thai electricity) is different from the rest of the world. As Thai plumbers know that Thai water and waste can flow up hill so nothing above is relevant in Thailand [ /sarcasm ]

Hoopoe wrote: ↑

August 22, 2018, 2:22 am

Is it just me , or am i missing something , the diagram shown, is venting a 3/4 inch water pipe (why ?) , it is not about venting the methane gases out of the s-e-p-t-i-c tank ,,,maybe i'm just gettin to owd fer this ,

I think that the OP is probably confused. Easy to understand why, with the BS he was told.

Or maybe he just likes fountains

Hoopoe wrote: ↑

August 22, 2018, 1:43 pm

sometimewoodworker wrote: ↑

August 22, 2018, 9:30 am

I think that the OP is probably confused. Easy to understand why, with the BS he was told.

I agree, but the confusion isn't limited to the OP (who, by disappearing from the thread, is probably agreeing - please keep coming, your questions elicit responses that will help others as well). The second diagram clearly states bathroom (singular) and the construction with a se.pt.ic tank below a slab (I suspect below an exterior path, just like my rented house in Udon) is typical of many Thai older builds with only a single toilet. So while all posts haven't been absolutely relevant to the OP's situation, they nevertheless provide solid guidance for inexperienced newbie builders in the LOS who may stumble over this thread.
Good luck with your builds.
ps. The house I have rented in Udon for ten years has two adjacent bathrooms, one with a water heater, pedestal toilet and a urinal. The second is used as a laundry with washing machine grey water exiting via a drain to the street sewer. The squat toilet in this room is (rarely) used for a pee if the main bathroom is occupied. There is no vent between the toilets or from the se.pt.ic tank. In ten years, with occupation of three people for several years, there has never been a problem of any kind - no syphoning issuues, nor any foul gas. AND we have never had to have it pumped out.