Is it a bad idea to join basin waste to rainwater like this..?

[harrypotter]

I'm redirecting some gutters to go to a soakaway and I've also got some two ground floor basin wastes already going to a soakaway. Can I join them all together so it's ultimately just one pipe going to the soakaway? The only thing that worries me is if the pipe gets backed up higher than the basins (dotted blue line) for whatever reason the basins might flood? In that case it might be better to just join both gutters and keep the basin waste seperate?

 

[opps]

I don't know the answer, but I suspect it would be illegal. I don't think dirty water is supposed to feed down to the water table.

 

[diy_fun_uk]

The following relates to Scotland, where you need to apply to SEPA if intending to discharge grey water into a soakaway.

Discharging grey water or liquid from composting toilets | Scottish Environment Protection Agency (SEPA)

How to register a septic tank.

www.sepa.org.uk

 

[noseall]

I've also got some two ground floor basin wastes already going to a soakaway

Are you not connected to the sewer? I.e. are you on a septic tank?

 

[evdamadiynot]

Bad idea even if permitted as you are polluting the rainwater which will disperse into the ground.

 

[Hugh Jaleak]

Grey water from a basin should be going to the foul drainage system. There is a reason why Waste pipework and Rainwater pipework are not able to be coupled together without a bodge.