Septic tank part 2

[algodon]

Had my plastic septic tank emptied 4 weeks ago it is now full of water, any ideas anyone how the water is getting into a sealed unit.

[stagecoach]

Apr 11, 2018 17:30:09 GMT 1 algodon said:

Had my plastic septic tank emptied 4 weeks ago it is now full of water, any ideas anyone how the water is getting into a sealed unit.

As septic tank is always full the tank is divided in two one side is the inlet and the other the outlet there is a weir inside that allows the solids to drop to the bottom and the liquid to flow over the weir and out via the tank outlet - it is normal when the tank is emptied that the contractor who empties it fills it with water - this not only enables the tank to work but also stops it from popping out of the ground

If the inlet side of the tank is over flowing then there is a blockage in the outlet pipework - good luck with that

[sidshady]

I expect the water is,nt soaking away because the ground is water logged and it is staying in the tank.check with your installer as to whether they made a proper soakaway for the waste water,if not you will have to have it emptied again.

[davexf]

Hola

The plastic septic tanks should be three part tanks and are designed to have water in them. When a contractor empties a tank they should take any solids out and then replace the "activators" which help bacteria break down the solids. The original activators will have been sucked out by the contractor.

In the normal course of use, a washing machine will put out 80 gallons of liquid minimum; combine this with the normal water usage of washing, showering, using toilets etc. and you will see around 80 to 100 gallons of water is used per person per DAY. Therefore you will quickly fill a tank.

The tanks are designed if you will, to "strain" the solids and allow the liquid to escape, the three part system making the water reasonably pure for garden usage. The bacteria will break down solids and nullify the harmful bacteria; the broken down solids will be allowed to escape.

Davexf

[algodon]

Mine is a two part plastic, fitted Nov 2016, been emptied twice last time 4 weeks ago and is today overflowing with water.

[davexf]

Hola

There are parts of Pago del Humo that in winter the water table is only a foot below the surface. Therefore the septic tank cannot empty. Where I am in Pago, it is always a minimum of two metres to water in winter and five metres in summer and this is usual for the vast majority of houses

Davexf

[algodon]

Thanks for that Dave, i dont know what i can do about it other than keep having it emptied and try restricting water going into it in very wet weather.

[londonpride]

Do you know if the septic tank has been installed correctly with a piped waste field that allows the waste water to percolate out into the outlying ground in an even manner and so spreading the over flow water evenly over an enlarged area at some distance from he tank.
As Dave says if your tank is located in very wet surrounding land the surrounding water table is allowing ground water to permeate back into the tank probably through the waste water discharge hole.

If no waste field has been installed ie away from the tank . Then the waste water is being discharged next to the septic tank and hence putting even more water next to the tank.

You could try installing a waste water pump and pumping the waste water away from the well. I’ve noticed that a number of locals do this on occasions. It won’t make you popular if you get the discharge point wrong and it might only provide temporary relief until it rains again . Good luck.
Ps. If you live on a small plot it’s probably unlikely that you will have a proper drain field due to lack of space.

[davexf]

Hola

A number of Spanish use a pump in the septic tank on a timer so that the tank is emptied every night; the septic tank therefore is sufficiently emptied to be able to shower in the morning. The Spanish say that it is "only the gray water" but in reality, any water in your septic tank is black water unless it comes correctly out of the overflow pipe.

The simple answer is to check your well to find the distance to water; that distance is likely to be the same on your whole plot.

Davexf

[algodon]

Just had tank emptied, when you could see the bottom of the tank you could see water flowing back into the tank from the outlet pipes that run up the garden, not just a trikle, like you had switched a hose on.
It has stopped now but more rain and it will start again because of the weight of the build of water already in the soil.
I think the alternatives are ( whilst the rain is around) is keep having the tank emptied every few weeks or buying a pump and do what you say Dave, but i would not want to pump the water back into the ground, so what do i do with the water ?

Any suggestions gratefully received.

[londonpride]

Hi. .your post seems to indicate that water is flowing back into the tank from pipes that run up the garden.That indicates that you have a waste discharge field somewhere in the garden .ie a proper soakaway fed by a pipe from the septic.This should be discharging the waste over some area but it should in any case be 25 metres min from the nearest well . ( yours or your neigbours). If the flow rate of water of water is returning to the septic at a considerable rate it either indicates a hole or holes in the discharge pipe to the field or the discharge field is located higher in the soil than the septic tank.ie running back downhill. The discharge area should be lower than the tank outlet pipe.
If you do have a discharge field with soakaway in theory it would make no difference to the status quo to pump your black water to that point.






Hopefully most of it will percolate into the soil via the soak away rather than finding its way back to the septic via the waste pipes..
It could be that water is just entering at the waste outlet and that no pipes actually exist to a distant point.

[algodon]

You are quite right londonpride, my pipe just runs the water into the garden only 5 metres from the septic tank as it then hits the concrete drive, there is no soakaway of any description.
The septic tank is about 12 metres from my well.
I assume you are saying that the outlet pipe is not angled downwards enough so the waste water plus rainwater in the ground is flowing back up the pipe back into the tank, which means digging to the pipe and reangling it.
Might be easier just to buy a pump and pump it out by bucket full and distribute it in the back garden in the winter.

[londonpride]

It will not make any difference just angling the pipe down as the water is flowing directly back into it because of the height of the ground water. You could try extending the pipe out as far away from the septic as possible and constructing a proper soak away . Keep as far way from well as you possibly can.
Soak away details can be ascertained from the web but generally they are at least 1 metre x1 metre x 1 metre excavation and filled with rocks and gravel. Pipe extends into middle of th excavation . The gravel etc aids the permeability of surrounding soil and permits easier drain away. Ps. Whatever you decide to grow at or near this point will flourish. A pump will work but if the ground is sodden and your water table is naturally high then you will be getting the pump out on a regular basis.

You could have a pump with flloat and waste pipes sunken into the garden controlled also by a timer. Set to pump out for say an hour a day at least it will allow you to do your morning ablutions. Another way to minimise the amount of water being received would be to drill a hole and divert the washing machine waste water onto the garden rather than sending it to the septic tank.
As Dave says any water pumped out is black (sewerage) water but the top surface water. If it is being refurbished by ground water will not be so bad to dump on your plants.

My neighbour has a similar set up with a permanently connected 1 inch flexible hose that he uses to pump out the water onto the adjacent farmers field. He does have permission to do this. Ps That part of the field exhibits larger crops than the other areas.

[algodon]

Thank you for this reply londonpride, i now have a better understanding of how all this works and the alternatives i have to alliviate the problem.
Will be on the case tomorrow. 

[londonpride]

Hi . Any works that can be done to assist the &drainage and minimise the amount of water actually entering the tank are of course helpfull.
However the overriding problem is no doubt the sheer amount of water entering from the high ground water level. With the cotinuation of the wet weather this will continue.
As Dave says a pump will provide the necessary temporary relief that you require if it can pump out faster than water is entering.
It should be said that septic tanks should never b installed in areas with high water tables and that is something the tank installers should have checked . In saying that I realise that the house location is what it is.

There is a solution to the ingress of water but it is expensive to install and maintain. Space permitting you could have a large capacity sealed cess tank installed.
Dependant upon the amount of waste generated it could necessitate emptying every six weeks or so . As it is sealed . Ie inlet only and no exit ground water cannot penetrate.

[londonpride]

Hi . Trying to think of something to resolve your problem on a temporary basis.
If you have decided to buy a pump and evacuate some space in the tank simply buy yourself a football or rugby bladder and fit it into the septic outlet . This should effect a good seal and stop the ground water entering until the ground water level drops and you can then remove it .

[leftie]

Just a thought! Would a water works check (non-return) valve work in this situation. I believe they are available in sizes from 2" to 12".

[londonpride]

Most non return valves operate because of a pressure against the valve holding it closed. Also the water will have some deritus in it you may find that it may actually obstruct the valve but it must be worth a try

[leftie]

There are valves specific to this use. Just Google " anti flood non return valve" and there is quite a choice.

[londonpride]

Leftie. Your suggestion seems to be the way forward as there are a number of these available specific to septic tank useage. They recommend a maintenance regime though to check for blockage or interfererence to flow caused by detritus.