I have an old fashioned underfloor septic with no rings or tanks. The toilet blocked and we removed the bowl and cistern to find it is blocked by roots. Somebody advised me to (carefully) use copper sulphate.  The only entrance to the septic is through the toilet and I have read the copper sulphate could damage the toilet(don't see how if I just wash it straight through). I can close the toilet for a period after I pit in the copper sulphate as I heard it can be harmful. Thanks for any advice 

4 minutes ago, Wongkitlo said:

I have an old fashioned underfloor septic with no rings or tanks. The toilet blocked and we removed the bowl and cistern to find it is blocked by roots. Somebody advised me to (carefully) use copper sulphate.  The only entrance to the septic is through the toilet and I have read the copper sulphate could damage the toilet(don't see how if I just wash it straight through). I can close the toilet for a period after I pit in the copper sulphate as I heard it can be harmful. Thanks for any advice 

You need to have the existing roots cleaned out first. The copper sulfate will help prevent new root growth but will do nothing to the existing roots already there. Won't hurt the toilet as you said, your flushing it straight thru

5 hours ago, Dan O said:

You need to have the existing roots cleaned out first. The copper sulfate will help prevent new root growth but will do nothing to the existing roots already there. Won't hurt the toilet as you said, your flushing it straight thru

Thanks for the info. It is an older Thai style of construction. They build a square of bricks and lay concrete beams on top. Fill the floor in and leave the hole for the waste. The only way to access it would be to demolish the building. It is only used in high season. The problem was the roots had blocked off the hole in the picture. The picture is taken after I removed them 🤩