Had to unblock two basins in one house today, one of which was barely draining at all, even when left overnight. Boiling water down the plughole didn't shift it, my fancy plunger didn't shift it, so I thought I'd crack open a can of this to see how well it worked before resigning myself to removing the trap and clearing the gunk out by hand.
In short, it's a great product; bit of gaffer tape over the overflow, held in place with one hand, and three 1 second squirts of this (the last of which was probably unnecessary) and the fully blocked basin was draining perfectly.
At around 14 quid a can, it's not cheap, but there's enough in there to do 4 or 5 blockages. For the amount of time and hassle it saves, it's worth it. I'll keep a can on the van and just use it by default in future.
Only downsides I can see are 1) that you should, I'd suggest, check the waste plumbing looks sound and not held together with silicone before using this, as the air blasts out with considerable force. I can imagine some of the shonkier bits of pipework you see might let go under the pressure, and:-
2) It was embarrassing how quickly I was in and out of the customer's house having used this to clear 2 sinks (about 20 minutes, most of which was chatting about the weather, etc). The guy had spent an hour emptying out the sink units so I could gain access to the pipework, and could barely believe it when I told him I was done. :)
