Our sink and bath are horribly blocked - standing water type blocked... Soda crystals and boiling water won't work as it's standing water and DH has done his best with the plunger...

So short of buying some really quite evil chemicals to pour down the drain and disolve the blockage (thinking mr.muscle) does anyone know of a more environmentally friendly and natural way of resolving the issue?
We did pour some bleach down last night

which does seem to have helped a little but I'd really rather avoid pouring large quantities of bleach into the water system...