Turns out our new place has a septic tank. Was trying to work out if the roof gutters went into a soakaway and found some plans on the councils site which showed a septic tank in the woods next to the house and sure enough there is a manhole with an air vent right inline with where the arrow on the plans pointed.

A little bit off further away and not inline there is another manhole, would this also be something do do with the septic tank, a second stage or maybe a separate one for the rain water as the soil type is clay so wondering if they have gone for a tank instead of a soakaway on that side of the house.

My reason for exploring is I am trying to work out a way to get my washine machine waste into the septic tank from the utility (dishwasher won the battle for the only space in the kitchen). Only ways to do it so far are:

1. Pipe round to outside kitchen drain – would end up with water stuck in the pipe as it would need to be low under the door and then pop back up into the drain.

2. Tank outside of utility with a dirty water pump to pump over the utility roof and into the kitchen drain – tank I have, pump I don’t.

3. Tap into the guttering down pipe next to the utility but I think this is a soakaway so a no go (although it does seem to head towards the second manhole)

4. Tap into the underground waste pipe (passes right by the washing machine) but this sounds fraught with danger of messing up.

5. Run a shallow waste pipe into the woods (6m or so) and pop the end into the vent on the septic tank which is quite big and has a couple of broken grills so a pipe would go in – is there some kind of baffle/trap that would prevent this?

No1 will just cause problems with your wm pump.
No2 could be done with a saniflo but they are a bit shit and for the cost another option may be better
No3 you need to establish if building control will ever notice. If its defo a combined system this would be ok but not normally done. If no one will ever know go nuts. We see lots of bodges like this.
No4 this is the proper option. If its a plastic pipe its a piece of piss. If its clay it can be an Arse as its virtually impossible to cut a clay pipe nicely insitu. You might luck out with a short section of pipe replacement which is actually not that bad.
No5 no baffle on a vent. Could be a goer. Don’t use too small a pipe or it will move settle and cause problems.

1. Agree, seems less than ideal as there is a door way to navigate too.
2. Have some spare 220 litre tanks so was thinking of a dirty water pump connected to a hose pipe into the drain.
3. would only do it if I can establish the guttering on that side goes to a tank of some sort. Thinking I should take the 2nd manhole cover up and spray the hose pipe into the guttering to see if it goes that way. Still not sure why there is 2 manholes though.
4. I suspect clay, I tried digging down where I think the pipe is before, got about 18 inches and still no joy so will try again at the weekend. I did wonder about diamond wheeling out a section of pipe and fitting a new plastic T section with rubber joins at each end. Or I could try and grind a hole in with a diamond cutter to prevent it cracking.
5. Seems to be the least destructive. Have some spare 40mm pipe I could use. There is a nice drop in the land to the tank and the vent as the house is built a bit higher up. Vent faces away from the house which is annoying but I did notice the clay pipe the vent is cemented into is a bit broken up so might be able to put an elbow down next tot he vent. I guess a bucket of water and take up the man hole is in order for that one.