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Posted: Mon Sep 11, 2006 8:12 pm
by gillyandgraeme
I have a query about drainage. We are contructing a pool at the end of the garden 70m from the house. Every month you need to 'backwash' the filter to clean it. This involves flushing water through the filter and out of a back wash pipe using the pool's pump, typically 1hp, for about 1 minute. This can produce a fair amount of water. I propose to run a 2" pipe back to the house and connect to a sewer pipe under the dining room (it's an old 1 system house).The first part of the run is gently downhill but the rest is level at best. In the lst few feet an outdoor clay drainage pipe crosses the proposed path and will necessitate an under and back up excursion for the pipe. My thinking is that if I've got 1hp of pumpbehind the flow, this slight uphill blip will not be of relevance? The next question is ,can I run a saniflow down the same pipe. Obviously there is going to be a slight collection of water (and things!) before the slight rise at the end, but does that matter if the pipe is being blasted clear once per month? I suspect that the loo would be for number 1's in the main. The saniflo outlet pipe would be isolated when the backwash is perfrmed to stop damage to the seals from the higher pressure water.
Posted: Mon Sep 11, 2006 9:16 pm
by lutonlagerlout
thismay help your understanding
it sounds a bit of a bodge to be honest,normally it is best to have a 1:60 fall on all pipes,saniflow are good but we mainly use them in loft conversions or cellars,70 m sounds a long way,i would speak to someone at saniflo mate
also any underground pipe should be 110mm,2 inch can block quickly
cheers tony ???
Posted: Mon Sep 11, 2006 10:09 pm
by Dave_L
lutonlagerlout wrote:also any underground pipe should be 110mm,2 inch can block quickly
cheers tony ???
Totally agree with what Tony has said.
Do you really want to be digging up the 2" pipework a month after it's been laid and has subsequently blocked? 
Posted: Mon Sep 11, 2006 11:00 pm
by gillyandgraeme
Dave_L wrote:lutonlagerlout wrote:also any underground pipe should be 110mm,2 inch can block quickly
cheers tony ???
Totally agree with what Tony has said.
Do you really want to be digging up the 2" pipework a month after it's been laid and has subsequently blocked?
Thanks for advice
I spoke to saniflow head office, they said it was not designed to work in these circumstances, and I spoke to our local bloke, who said it would work but there would obviously be a bit of a 'reservoir' in the pipe behind the uphill bit at the end. This uphill bit is still some way below(in height) the starting point, but as I said the distance is v long and the gradient v shallow. To be honset it is a bit of a bodge. We may have to give up the idea of a loo (although sounded worth a go to stop people pissing in the pool!) You mention the 2" pipe blocking. If this was just used for the backwash, no saniflo, do you think I'd still have trouble. The other option is a soakaway near the pool. We are on chalk. My concern is how big this would have to be as a lot of water comes out of the back wash, very quickly.