Septic Tanks

[Encid]

I was searching the forum for information on septic systems, and the only topic I could find (which did have some good information in it) had been archived so I am unable to reply in it.

 

I am curious how you guys have set up your septic systems for both black water and grey water.

 

Any feedback would be most appreciated.

 

And just for laughs, if you are going to get an off-the-shelf septic tank, make sure it has features like this one!

 

 

[bankruatsteve]

We started with two cesspits, one for black, one for grey.  It turned out that the idiot builder connected the kitchen sinks and the washer to the black and we were constantly needing to get them sucked out.  First thing I did was connect the black to the grey (with inverted PVC) and added a leach pipe to the grey.  Note:  a leach field is what makes a "septic" system.  I then diverted the washer output and the kitchen sink output to the garden.  Everything has been good for 6-7 years now and never have to get the tanks sucked.

[Encid]

This is the type of system I am considering installing:

(the photo was copied from a previous topic now archived)

 

 

 

This is a schematic of the proposed system:

 

[Encid]

The reasons for installing both a grey water tank and a soakaway are several.

 

Firstly, our current home was built approximately 15 years ago now, and the moobaan was developed from a previous rice farm.

It was filled (approx 500 mm only) compacted, left for a few years, then the developer subdivided the block and planned and built 50 odd houses.

 

We first learned about the water table under the land when we constructed our swimming pool... the hole was about 2 metres deep and it kept filling up by a couple of hundred mm every night.

The pool fabricator had quite a task to keep the hole drained until he had the concrete base and sides of the pool poured.

And it was the cool dry season when it was built.

 

Anyway, back to septic systems...

Because the water table was so high in our area, the grey water ring tank never emptied... the level inside was always about 1 metre below grade level.

And as septic systems operate, the overflow from the septic tank flows into the grey water tank which is supposed to allow the water to dissipate into the surrounding soil.

But they do not work if you have a high water table and heavy rains for several days.

Under those conditions the grey water overflows... onto your garden or wherever it can flow.

Consequently we have to empty our septic tank and grey water tank about twice a year.

 

Not much else we can do about it... unless anyone here has some suggestions?

 

The new house we are planning on building is up-country... on a filled parcel of land that is currently being used for rice farming.

Finished surface level of the land will be about 500mm above the highest recorded flood level, and the house will be constructed 1 metre above that.

It will have 4 bathrooms... 2 downstairs and 2 upstairs.

So I am thinking of having 2 septic systems... 1 at each end of the house.

 

I did a little research, and discovered the following information:

 

 

As you can see (and probably expected), most of the wastewater is grey water... but what I found surprising was the volume.

No wonder our current grey water tank is nearly full all the time... one tank is simply not enough for that volume of water.

 

So our new design has both a grey water tank and a soakaway for each septic system... and I am thinking of having a dedicated grey water tank and soakaway just for wastewater from the kitchen(s) and washing machine.

 

Any comments?

 

[Encid]

Do any of you use your grey water on your gardens or lawns?

 

With reference to the data in the information from Mahidol University above, the BOD loadings (organic wastewater biological treatment method is characterized in total volumetric BOD loadings) from the kitchen and washing machine are very high, probably due to the amount of detergents used, and is probably not suitable for use on gardens and lawns.

 

But the grey water from bathrooms (and I'm also thinking of collecting the water from the air conditioning condensers) should be OK.

 

Any thoughts?

[MJCM]

10 minutes ago, Encid said:

But the grey water from bathrooms (and I'm also thinking of collecting the water from the air conditioning condensers) should be OK.

 

Any thoughts?

Re:  Bathrooms - Shampoo / Soap??? So not a good idea IMHO

Re: Aircon, I think it's very clean water so IMHO good idea, just have a bucket under the pipe and regularly empty it on your plants / garden

[sometimewoodworker]

52 minutes ago, Encid said:

The reasons for installing both a grey water tank and a soakaway are several.

 

Firstly, our current home was built approximately 15 years ago now, and the moobaan was developed from a previous rice farm.

It was filled (approx 500 mm only) compacted, left for a few years, then the developer subdivided the block and planned and built 50 odd houses.

 

We first learned about the water table under the land when we constructed our swimming pool... the hole was about 2 metres deep and it kept filling up by a couple of hundred mm every night.

The pool fabricator had quite a task to keep the hole drained until he had the concrete base and sides of the pool poured.

And it was the cool dry season when it was built.

 

Anyway, back to septic systems...

Because the water table was so high in our area, the grey water ring tank never emptied... the level inside was always about 1 metre below grade level.

And as septic systems operate, the overflow from the septic tank flows into the grey water tank which is supposed to allow the water to dissipate into the surrounding soil.

But they do not work if you have a high water table and heavy rains for several days.

Under those conditions the grey water overflows... onto your garden or wherever it can flow.

Consequently we have to empty our septic tank and grey water tank about twice a year.

 

Not much else we can do about it... unless anyone here has some suggestions?

 

The new house we are planning on building is up-country... on a filled parcel of land that is currently being used for rice farming.

Finished surface level of the land will be about 500mm above the highest recorded flood level, and the house will be constructed 1 metre above that.

It will have 4 bathrooms... 2 downstairs and 2 upstairs.

So I am thinking of having 2 septic systems... 1 at each end of the house.

 

I did a little research, and discovered the following information:

 

 

As you can see (and probably expected), most of the wastewater is grey water... but what I found surprising was the volume.

No wonder our current grey water tank is nearly full all the time... one tank is simply not enough for that volume of water.

 

So our new design has both a grey water tank and a soakaway for each septic system... and I am thinking of having a dedicated grey water tank and soakaway just for wastewater from the kitchen(s) and washing machine.

 

Any comments?

 

150 litres per day per person is on the low side of normal usage. Don’t forget you must multiply that figure by the number of people, and for teenage girls the shower usage is most likely 5 times greater ????  Ask any parent with one. ???? 

for our house we have septic tanks and a leach pipe for the toilets, everything else goes directly onto the garden, SWMBO is happy with that. The only thing to be careful of is oil/grease from the kitchen.

[bankruatsteve]

As I mentioned in my previous post, we have the kitchen sink discharge go to the end of a garden.  It doesn't smell or seem to bother anything.  Actually it seems to promote spontaneous growth; the latest being a tomato plant that delivered 20 some small tomatoes.  The washer discharge goes to another area that is mostly the gravely clay common here.  That does not seem to have an effect on anything one way or the other.  IMO much better than going to the septic.

[Encid]

9 minutes ago, sometimewoodworker said:

The only thing to be careful of is oil/grease from the kitchen.

Is that why Thaiwatsadu sells grease traps for?

See here.

[bankruatsteve]

12 minutes ago, Encid said:

Is that why Thaiwatsadu sells grease traps for?

Have you ever had a grease trap?  For me, never again.  A lot easier to just not put grease down the drain.

[sandyf]

1 hour ago, Encid said:

Any comments?

Plenty, but not a lot of time at the moment.

Waste water disposal was the main problem getting the plans approved. There was a bit of ignorance on my part and the builder got confused. He was very good to us so I let him carry on and I altered it myself after.

What I ended up with is 3 underground plastic tanks, the first is black water, and the overflow goes to the second,  as does the grey water, and the overflow from there goes to the third. This tank, I dug the hole and planted it myself. The water from this tank is pumped out to the garden. I had it on a float switch to start with but that burnt out with the humidity in the tank. The black water tank has never been emptied since the house was built 12 years ago.

I think I have some septic tank info and some photos,  will try and dig them out but not till Mon at the earliest, going down to Pattaya tomorrow.

[Will B Good]

Going crazy trying to work out what we have in our house, as the wife won't explain properly and the builder doesn't speak English.

 

Each of the shower rooms has, in the garden, a raised concrete plinth. The plinth contains one medium sized manhole cover and two, much smaller covers, in line with each other and the larger cover.

 

The wife says 'everything' from the shower room goes into the tank beneath the medium sized manhole cover. This swirls everything around to clean it (patently nonsense, but I know to just smile and nod) and once cleaned the clean water then goes into a tank or tanks under the two smaller covers.

 

She insists the first tank never needs to be cleaned out as the 'stuff' just disappears. The clean water under the two smaller covers has to be 'sucked out' when full.

 

Can anyone make sense of that? PLEASE.

[Will B Good]

16 minutes ago, sandyf said:

Plenty, but not a lot of time at the moment.

Waste water disposal was the main problem getting the plans approved. There was a bit of ignorance on my part and the builder got confused. He was very good to us so I let him carry on and I altered it myself after.

What I ended up with is 3 underground plastic tanks, the first is black water, and the overflow goes to the second,  as does the grey water, and the overflow from there goes to the third. This tank, I dug the hole and planted it myself. The water from this tank is pumped out to the garden. I had it on a float switch to start with but that burnt out with the humidity in the tank. The black water tank has never been emptied since the house was built 12 years ago.

I think I have some septic tank info and some photos,  will try and dig them out but not till Mon at the earliest, going down to Pattaya tomorrow.

This sounds like my system I was asking about!!!

[Encid]

20 minutes ago, bankruatsteve said:

A lot easier to just not put grease down the drain.

Actually I have trained my wife and her SIL not to do that too.

The used cooking oil (Thai's just love to fry everything except som tum hey?) goes into empty cooking oil containers and they are disposed of with the garbage.

Not sure how we're going to dispose of stuff like that when we're up-country though...

 

I would not have thought that the minimal amount of residual grease or oil on frypans, cooking utensils, plates etc. and detergents would be significant enough to contaminate the grey water tank so much that it would be detrimental to plants.

[Will B Good]

16 minutes ago, Encid said:

Actually I have trained my wife and her SIL not to do that too.

Well impressed!

[MJCM]

47 minutes ago, bankruatsteve said:

Have you ever had a grease trap?  For me, never again.  A lot easier to just not put grease down the drain.

May I ask why?

[Encid]

31 minutes ago, sandyf said:

Waste water disposal was the main problem getting the plans approved.

I have heard that anything "non-standard" can be scrutinized for a long time and that approval can be difficult.

 

Apparently there are 3 government agencies related to laws and regulations for on-site treatment facilities... 1) the Ministry of Interior (MOI), 2) the Ministry of Natural Resources and Environment (MONRE), and 3) the Ministry of Public Health (MOPH).

 

[Encid]

6 minutes ago, Will B Good said:

Well impressed!

A little practical demonstration never hurts lol.

We were living (renting) in Bangkok many years ago and her SIL was our maid.

There was always a severe problem with drainage in the area with flooding and huge rats would come out of the storm drains whenever it rained.

One day (closer to a week actually) a council truck turned up, blocked off the road at both ends, took off all the storm water drain covers, and sucked out all the gunk inside. Some workers even had to climb down into the drains and shovel the gunk out manually.

The smell was horrendous!

My SIL asked one of the workers where all the gunk came from and he explained that the majority was from food vendors who poured their used cooking oils down the drains.

I'm sure that the practice still continues in Bangkok, but it was a valuable lesson for my wife and her SIL.

[Will B Good]

3 minutes ago, Encid said:

A little practical demonstration never hurts lol.

We were living (renting) in Bangkok many years ago and her SIL was our maid.

There was always a severe problem with drainage in the area with flooding and huge rats would come out of the storm drains whenever it rained.

One day (closer to a week actually) a council truck turned up, blocked off the road at both ends, took off all the storm water drain covers, and sucked out all the gunk inside. Some workers even had to climb down into the drains and shovel the gunk out manually.

The smell was horrendous!

My SIL asked one of the workers where all the gunk came from and he explained that the majority was from food vendors who poured their used cooking oils down the drains.

I'm sure that the practice still continues in Bangkok, but it was a valuable lesson for my wife and her SIL.

Yes......a few instances of 'fat burgers' having to be cleared from the sewers in London......one was 330 tons......yes 330!!!!!!

[bankruatsteve]

13 hours ago, MJCM said:

May I ask why?

RE grease trap:  Had one in the states years ago and never again.
First, it promotes dumping used oil, grease, etc. down the sink and that is bad, very bad.  Second, it smells terrible.  Third, it needs periodic cleaning out which is a disgusting process.  Did I mention the smell.  Fourth, if you put off the cleaning or forget, you end up with a problem much worse than if it was never there.

[sometimewoodworker]

56 minutes ago, bankruatsteve said:

you end up with a problem much worse than if it was never there.

If the grease is getting into the black septic tank I really think that the results will be far worse than a smelly grease trap.

[Will B Good]

On 3/19/2022 at 2:48 PM, Encid said:

This is the type of system I am considering installing:

(the photo was copied from a previous topic now archived)

 

 

 

This is a schematic of the proposed system:

 

Why does it say....."immediately fill with water"?

[Encid]

1 hour ago, Will B Good said:

Why does it say....."immediately fill with water"?

 

[sometimewoodworker]

2 hours ago, Will B Good said:

Why does it say....."immediately fill with water"?

Because if you don’t then either ground water or the next rain will float it.

[Will B Good]

3 hours ago, Encid said:

 

Cheers.............. watched a few of his videos before.......... they're so bad they're good.

[userabcd]

20 hours ago, Will B Good said:

Why does it say....."immediately fill with water"?

Because if it is underground the empty tank could collapse from the external pressure by the surrounding filling, if there is groundwater present then the empty tank could float.

[userabcd]

For anyone interested here is a link to Cotto products for grease traps, wastewater tanks and larger G type wastewater tanks.

 

COTTO BROCHURE