We have a reoccuring problem with foul smelling drains in the back yard. Its not a constant problem but seems to come around every now and again. There is no pattern to when it smells, ie it doesn't just happen when its been raining or sunny. The smell is coming through the sink and washing machine so can be smelt in the kitchen, although not the bathroom, we have an extension running off the rear of the house with the bathroom and kitchen attached.
We have tried chemical cleaners etc with no joy, it seems to just hide the source of the problem. The drains do not appear to be blocked as they don't overflow, so I don't think it is a blockage causing the problem, i've read it could apparently be a cracked pipe, although I would imagine I would see subsidence or wet ground, we have a paved drive.
Don't really fancy paying dyna rod an extortionist amount as I don't trust them. So not sure if anyone has any ideas?