Daf Posted April 24, 2022 Share Posted April 24, 2022 I have an onion shaped septic tank that's well over 22 years old and the baffle that separates the lower chamber from the top chamber has come loose and is now flopping about within the tank. I think some clumps of fat have now worked their way down the soakaway/drainage field and things have become sluggish with waste water throughput. I didn't install the tank or drainage field so have no idea what it looks like underground. I'm thinking of installing a new bullet shaped septic tank and drainage field as what I've read on the interweb, the existing tank isn't repairable. I can decommission the old tank, drain it, knock some holes in it, chuck in some rubble and cap it off etc so not too worried about that and I have the space to put in a new tank and drainage field in parallel before switching over. All good. (1) I'm looking at the Graf Carat 3750l tank. Does anyone have experience of this tank? Should I also look at Marsh's or Klargster offering? Any others I should consider? (2) The inlet for the new Graf tank seems to be around 600mm below ground. I have an inspection chamber outside my property that collects three waste feeds from around the house. When the house was built this drain was connected to the mains but the effluent had to be pumped up hill to the nearest mains pipe. After several failures and leaks, the original owner disconnected from the mains, removed the pump and switched to a septic tank. I think this is the reason why the pipe running to the existing tank starts at 82cm below ground at the inspection chamber and terminates at 1.5m at the onion septic tank. That is very low and defeats the purpose of using a low profile tank. So, I suspect the whole lot has to come up by quite a bit by the looks of it and I'll have to dig down to find the original pipe height as it leaves the house - hoping that it is much higher I suspect! If it doesn't where do I go from here? Another Onion style tank? Link to comment Share on other sites More sharing options...
ProDave Posted April 24, 2022 Share Posted April 24, 2022 SERIOUSLY look at instead installing a small waste treatment plant. Not very much more expensive, no larger, and the drainage field can be about 20% smaller. Far cleaner output and much less likely to clog the drainage field. The only downside is needing an electricity supply so need to run a cable to it. If you take this advice, choose one that works with an air blower and not one that has moving mechanical parts. Link to comment Share on other sites More sharing options...
TonyT Posted April 24, 2022 Share Posted April 24, 2022 (edited) Discuss with EPA/SEPA/ Local Authority. best get their input Edited April 24, 2022 by TonyT Link to comment Share on other sites More sharing options...
nod Posted April 25, 2022 Share Posted April 25, 2022 We have just installed a Matrix TP for the second time Easy to install Problem free running Nine Pop ££2800 Link to comment Share on other sites More sharing options...
ToughButterCup Posted April 25, 2022 Share Posted April 25, 2022 11 hours ago, Daf said: ... Any others I should consider? ... BioPure Why? Minimal moving parts. Reading your post, it occurs to me to ask why are you fighting with a septic tank that doesn't work? Ignore it. How? Install some other system in parallel , and then redirect the flow to the second tank. Remove the original, fill in, dispose of it at leisure. Link to comment Share on other sites More sharing options...
joe90 Posted April 25, 2022 Share Posted April 25, 2022 I installed a Vortex and can’t fault it https://www.totalwastewatersystemsuk.co.uk Link to comment Share on other sites More sharing options...
ProDave Posted April 25, 2022 Share Posted April 25, 2022 And to complete the list, Conder and Graff are 2 more air blower treatment plants. On a technical level there is not much to choose between them so often people find the choice is whichever one you can get the best deal on including delivery to your house. In my case I chose conder because I got a good price from Travis Perkins and that included delivery and offload by their own waggon. Link to comment Share on other sites More sharing options...
Russell griffiths Posted April 25, 2022 Share Posted April 25, 2022 I used a Graf tank, very robust tank, made in Germany. Mine is 1.1 below ground level, 1.5 will be a hell of a hole and you might require a pumped outlet to come up to your drainage field. Just check your terminology. You need a treatment plant, not a septic tank. Link to comment Share on other sites More sharing options...
nod Posted April 25, 2022 Share Posted April 25, 2022 I most have Zero moving parts Link to comment Share on other sites More sharing options...
saveasteading Posted April 25, 2022 Share Posted April 25, 2022 To complete the completed list, i like Marsh. A person to talk to at the actual factory to help with the spec. The last time i used them they phoned before delivery, and it turned up on a trailer behind a landrover. They now sell only through BMs but deliver direct or to the BM. No moving parts. Link to comment Share on other sites More sharing options...
Daf Posted April 25, 2022 Author Share Posted April 25, 2022 Why do I need a sewage treatment plant? I cannot discharge to a water course and have to discharge to a drainage field. A septic tank is half the price of a sewage treatment plant, has no moving parts, no need for an electrical connection, is bigger and therefore has a capacity that is more tolerant of cleaning chemicals. The existing onion tank and drain field has behaved perfectly for 22 years until the baffle broke. Why change? Link to comment Share on other sites More sharing options...
Daf Posted April 25, 2022 Author Share Posted April 25, 2022 5 hours ago, Russell griffiths said: I used a Graf tank, very robust tank, made in Germany. Mine is 1.1 below ground level, 1.5 will be a hell of a hole and you might require a pumped outlet to come up to your drainage field. Just check your terminology. You need a treatment plant, not a septic tank. I know that the drain from the kitchen is around 15cm below the surface but runs into an inspection chamber that is 82cm below ground. I'm assuming/hoping that the bathroom connection and downstairs toilet are the same. A bit of digging will confirm this and if they are the same then I can can redesign the pipework that will work with a low level bullet septic tank at minimum depth. Still don't get the support for Sewage treatment plant over a septic tank. I have nothing against sewage treatment plants but for this installation I can't see the point? Link to comment Share on other sites More sharing options...
dpmiller Posted April 25, 2022 Share Posted April 25, 2022 You can get riser extensions for many plants, which gives more flexibility on the invert. Link to comment Share on other sites More sharing options...
Roger440 Posted April 25, 2022 Share Posted April 25, 2022 3 hours ago, Daf said: Why do I need a sewage treatment plant? I cannot discharge to a water course and have to discharge to a drainage field. A septic tank is half the price of a sewage treatment plant, has no moving parts, no need for an electrical connection, is bigger and therefore has a capacity that is more tolerant of cleaning chemicals. The existing onion tank and drain field has behaved perfectly for 22 years until the baffle broke. Why change? Im with you 100% Knowing what i know now, id never fit a treatment plant over a septic tank given a free choice. Ive got a vortex. Which we fitted. The reality is it needs maintenance, uses electricity and makes noise. They all will to some extent. Septic tank is passive. Just sits there. Can you not fix the baffle, and renew the drainage field? Link to comment Share on other sites More sharing options...
dpmiller Posted April 25, 2022 Share Posted April 25, 2022 septic tanks need maintenance too, and more often than a TP Link to comment Share on other sites More sharing options...
SteamyTea Posted April 26, 2022 Share Posted April 26, 2022 Rules here https://www.gov.uk/permits-you-need-for-septic-tanks Link to comment Share on other sites More sharing options...
SteamyTea Posted April 26, 2022 Share Posted April 26, 2022 If you zoom in to the bottom left corner, the sea is brown. Can tell holiday week is over, cheapskate holiday park owners have discharged the sewage treatment plant. And this is in one of the most desirable places in Cornwall. Link to comment Share on other sites More sharing options...
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