Replaced Cesspit and Reused for Rainwater Harvesting

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Replaced Cesspit and Reused for Rainwater Harvesting
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kGarden

Joined: 01 Dec 2014
Posts: 178
Location: Suffolk, UK

Posted: Fri Jan 09, 15 5:06 pm Post subject: Replaced Cesspit and Reused for Rainwater Harvesting

Putting this here as a description of what we have built rather than hijacking a thread which is discussing rainwater harvesting for loo flushing:

https://forum.downsizer.net/viewtopic.php?p=1426833#1426833

We are not on mains drains, and our cesspit was ancient and liable to become a stinky problem without much warning and it would be ALL MY FAULT! so on that basis I transferred some coins from one pocket to another and made an economic argument, to myself, to replace the cesspit.

We put a Klargester digester-thingie in, the outfall from which is "clean". I am now in a position to reuse 100% of the water that goes through the house as irrigation water on the garden. This doesn't help save water in Winter (which rainwater flushing loo would do)

We were fortunate in that the rainwater drains, from downpipes, ran close to the foul water ones, so we re-routed the foul to the new Klargester and the rain water into the old foul pipes and thus onward to the old cesspit.

I found an article on an Australian water company website recommending an application rate for (Swimming Pool) Chlorine to kill the nasties in a discontinued cesspit (we had the sludge emptied first), and I figure that bringing the rainwater into the first chamber will allow the silt and muck to settle out thus water pumped out of the final chamber will be relatively clean and not need a lot of filtration before pumping into irrigation system (mostly leaky-hose)

I current have a dozen IBC's, which we previous used to link together and position under downpipes to catch rainwater, which will be the storage short term; longer term I'm looking to get a 18' diameter grain silo and Butyl liner.

I have a pipe running from the Klargester outfall pump to the nearest rainwater downpipe gulley, and another to the ditch. So I can put household waste water into the irrigation system if necessary (Summer drought), but my preference is to water the plants with rainwater and thus by default I would route the Klargester outfall to the ditch.

Treacodactyl
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 25795
Location: Jumping on the bandwagon of opportunism

Posted: Sat Jan 10, 15 12:00 pm Post subject:
Interesting. I might need to do something similar in the future. Did you put in the Klargester yourself or get a company in to do it? Would it be possible to give a rough idea of prices? I am wondering what to do with the old cesspit once it's been replaced.

kGarden

Joined: 01 Dec 2014
Posts: 178
Location: Suffolk, UK

Posted: Sat Jan 10, 15 12:51 pm Post subject:

Treacodactyl wrote:

Did you put in the Klargester yourself or get a company in to do it?

The company would have been happy to install it, but their cost had to include transporting diggers etc,. to site and we had builders (and appropriate kit) onsite at the time, so I got the builders to do it.

Quote:

Would it be possible to give a rough idea of prices?

Can't remember with any details now, but must have been of the order of �5K

You could do it yourself, but I read stories of tanks lifting out of the ground - particularly after emptying, at a time when water table was high. Mine is encased in a lot of concrete, although I suppose the alternative it to re-fill with mains water after emptying - provided you / future owners know that they have to ...

Mate of mine decided that any repair/replace to the electric motor in the tank was an unpleasant job has chosen a brand that only uses aeration. He has a small compressor pump in a shed and an air pipe to the vessel, so any future maintenance/repair will be in his shed. I like the sound of that, but if mine goes wrong I will "get a man in" so not particularly bothered.

That mate also told me (although not sure if he did it that way) that it is possible to have an existing cesspit lined. Some sort of tank / chamber is inserted into the existing cesspit to provide a modern system (i.e. clean water outflow) whilst reusing the existing cesspit, and the existing foul water pipework that flows into it. I could ask him for details if anyone is interested - its perhaps an answer to your next question, but in my case would not have provided me with a rainwater filter & store.

Quote:

I am wondering what to do with the old cesspit once it's been replaced.

All reports I read, on Government websites around the world, mostly American but with the exception of the Aussie one that said to put Chlorine in it and use it as a water store, said something like "Hugely dangerous, fill with sand" ..

Re: Klargester

Watch out for the height of the inlet and outlet pipes. If you are on the side of a hill you won't have a problem, we are very flat here and getting a suitable fall for the pipes is always a problem. Alternative is pumping, but pump failure means overflow and all sorts of problems with contamination if that gets into any storage tanks.

dpack

Joined: 02 Jul 2005
Posts: 46207
Location: yes

Posted: Sat Jan 10, 15 7:34 pm Post subject:

a hole and a liner is fairly cheap,perhaps backfill the old tank is the best option

i dug a worm hole for new drains through a pre victorian cess pit that was under a useful building and that still had a smell which changed and that might have indicated "active"things,
chlorine or oxygen "bleach"might work but a new hole ,a liner and a few lengths of pipe would be a safe and not too expensive option.

dpack

Joined: 02 Jul 2005
Posts: 46207
Location: yes

Posted: Sat Jan 10, 15 7:36 pm Post subject:
the hugely dangeroos might be i relation to the h2s gas that collects in such holes

kGarden

Joined: 01 Dec 2014
Posts: 178
Location: Suffolk, UK

Posted: Sun Jan 11, 15 9:48 am Post subject:

I don't know the volume of our old cesspit, but the Klargester installer bloke said it was very unlikely to be more than 5,000L - I asked the question wanting to know how much irrigation storage it would give me, clearly "not enough" on its own.

I am presuming that the ground water will seep back into it as we pump it out, and we don't need much in the way of rainfall on the house, sheds and barn (all piped to the rainwater drains) to refill 5,000L (1" of rain on 200 sq.m. would give 5,000 Litres).

When I originally Googles there was plenty of material about the residual bugs, and that Chlorine would only kill the ones in the tank itself and there would be more some distance away in soil / finger drains. Forgive my ignorance, but aren't they going to need fresh sewage to eat in order to multiply?

Mine is only for irrigation, and I wasn't planning, initially at least, to use it on the veg patch (luckily the irrigation distribution backbone pipe, off the water main, starts by the vegetable patch and then continues up the garden and the cesspit / storage area is at that end, so a single strategically placed isolating valve in the pipe enables me to use mains on the veg patch and grey water on ornamental garden.

But it has got me thinking that I should configure the pump, which moves water from Old Cesspit to Above ground store, to only pump when cesspit is (say) 75% full (i.e. during heavy rain) so that there is always plenty of water in the cesspit and chance of bugs / H2S would then be reduced?

Ty Gwyn

Joined: 22 Sep 2010
Posts: 4613
Location: Lampeter

Posted: Sun Jan 11, 15 3:52 pm Post subject:
Just a point of clarification, Septic Tanks drain, Cesspits don`t,they need pumping out.

Treacodactyl
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 25795
Location: Jumping on the bandwagon of opportunism

Posted: Sun Jan 11, 15 4:19 pm Post subject:

kGarden wrote:

Can't remember with any details now, but must have been of the order of �5K

Thanks for that. Prices seem to be around �10k to get a company in to install one and I think you can easily add on a few more thousands if you need to move much of the waste pipes and for dealing with the old tank.

On the note of dealing with an old tank, anyone know what state it would be in if it's not been emptied for.... decades?

kGarden

Joined: 01 Dec 2014
Posts: 178
Location: Suffolk, UK

Posted: Sun Jan 11, 15 5:35 pm Post subject:

Ty Gwyn wrote:

Just a point of clarification,

Septic Tanks drain,

Cesspits don`t,they need pumping out.

Sorry, I've been slack with terminology. My Septic Tanks needed pumping out once a year, or so - many years we didn't bother - and had a system of finger drains - almost certainly blocked, over the years, but even so it didn't seem to be giving any bother

Treacodactyl wrote:

The digesters ... produce cleaner water that doesn't need a large soakaway. As far as I understand it.

I don't know how they work, but from what I have seen:

There are some big rotating pre-impregnated discs inside, they rotate slowly in-and-out of the liquid, giving whatever is growing on them a chance to catch its breath.

The chamber is physically divided into Inlet and Outlet chambers to a level above the outlet port. As part of the rotation there is a small "cup" on the inlet chamber side which scoops up a cupful and tips it into the outlet side. I suppose if there is not much inlet top-up that would empty the inlet side, into the outlet side, over time (its also possible that there is a connecting hole lower down so that the level stays constant). The outlet side remains "full" because the outlet port is high up.

Quote:

kGarden wrote:

Can't remember with any details now, but must have been of the order of �5K

Prices seem to be around �10k to get a company in to install one

The price I paid could easily have been that. We had a lot of building works going on, and I just took a huge single intake of breath at the total figure!

Payback is "forever" though, compared to just irrigating the garden with potable mains water

I think rainwater harvesting should be subsidised - better than building more reservoirs and cleaning up water to then just chuck it on people's gardens.

Quote:

On the note of dealing with an old tank, anyone know what state it would be in if it's not been emptied for.... decades?

I don't think we emptied ours (i.e. didn't realise we needed to / get around to / have it on the calendar) for 5 years after we moved in. Nothing happened. Tanker came back a second time to properly empty it though.

I think that if there was an issue drains would be backing up and there would be a smell, particularly in periods of drought, to alert you to a problem.

Ty Gwyn

Joined: 22 Sep 2010
Posts: 4613
Location: Lampeter

Posted: Sun Jan 11, 15 7:52 pm Post subject:

Treacodactyl wrote:

They both need pumping out, cesspits it's all the water and solids, septic tank it's mainly the solids. The digesters also need solids pumping out but they produce cleaner water that doesn't need a large soakaway. As far as I understand it.

That depends on several matters,like how big the tank is,how big a family using it,and how was it built,and how good the soakaway system is,yes i have built a few over the year`s.

On the note of dealing with an old tank, anyone know what state it would be in if it's not been emptied for.... decades?

Like above,it depends on how it was built and materials used.

dpack

Joined: 02 Jul 2005
Posts: 46207
Location: yes

Posted: Sun Jan 11, 15 7:58 pm Post subject:
not emptied for decades and scoured would be ok with an impervious tank made of metal or fiberglass or plastic if it is brick or similar chances are the local earth has some interesting spores that thing i dug through was active after 150 yrs

Treacodactyl
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 25795
Location: Jumping on the bandwagon of opportunism

Posted: Sun Jan 11, 15 8:12 pm Post subject:

Ty Gwyn wrote:

That depends on several matters,like how big the tank is,how big a family using it,and how was it built,and how good the soakaway system is,yes i have built a few over the year`s.

A septic tank will need emptying at some point though as the solids don't, or shouldn't go anywhere and they can't physically be turned into liquids?

I know the emptying intervals will greatly depend on use, design etc but unless they are unusually large and hardly used if you don't empty them then the sewage slugs is going to eventually empty through the soakaway and then spill out into the surrounding soil.

I know some people think they never need emptying but that's just a myth. Confirmed that with my local council enforcement officer.

Ty Gwyn

Joined: 22 Sep 2010
Posts: 4613
Location: Lampeter

Posted: Sun Jan 11, 15 8:13 pm Post subject:
What material were the London sewers originally built of? Good quality engineering bricks would be fine.

Nick

Joined: 02 Nov 2004
Posts: 34535
Location: Hereford

Posted: Sun Jan 11, 15 11:17 pm Post subject:

Treacodactyl wrote:

Ty Gwyn wrote:

That depends on several matters,like how big the tank is,how big a family using it,and how was it built,and how good the soakaway system is,yes i have built a few over the year`s.

A septic tank will need emptying at some point though as the solids don't, or shouldn't go anywhere and they can't physically be turned into liquids?

Everything can be turned to gas. Eventually.

Falstaff

Joined: 27 May 2009
Posts: 1014

Posted: Mon Jan 12, 15 1:32 am Post subject:

Treacodactyl wrote:

I know some people think they never need emptying but that's just a myth. Confirmed that with my local council enforcement officer.

YAWN

The Victorians may not have known much - b ut they knew enuff to keep sewaGE SWEET -

And enuff to hypothesize that CO2 + Global warming !

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