stuart noble wrote:

How to clear it completely?

Tip caustic soda crystals fllowed by kettle of hot water, down it,
wearing usual safety nanny googles and gloves, and cover with a plastic
bin liner till it stops fizzing.

Then leave for an hour or two, then flush.

If you suspect heavy pipe scaling pour a half gallon of brick acid down
it and wait a day till it stops fizzing.


Neither of which will have any effect on the typical household blockage
which, as in this case, is only partial. The chemicals will just flow past
it a little slower than normal.
Caustic unblockers are designed for people who pour things like cooking oil
down the loo. A lot of cellulose based products actually swell in alkali.
And scale sufficient to block a soil pipe? Jesus, that *would* be hard
water.


Well, I had a case once...

basically teh loo outfall was about 1/2 diameter due to years of scale,
and into that got wedged a lot of loo paper and fecal matter.

Now teh caustoc got rid of te fecal matter, and the acid got rid of the
scale - albeit taking several applications over several weeks. And
sanit(ar)y was restored.

My experience is that usually a blockage is not just one thing, but
many, and all need to be cleared.

With a partially blocked toilet, the chemicas flow slowly and collect
where the block is.

Once its mostly cleared it washes away unless there is something really
solid there. Might be a tree root, might be scale, might be a disposable
razor jammed up with a plastic beaker.

Acid and alkali will bugger up almost anything organic - if one doesn't
the other will.

The only stuff that gets left is generally physical plastic objects, and
sometimes metal ones, but acid often erodes those as well - enough to
free them.

Pushing a hose backwards up the pipe towards the blockage from
downstream is also very very effective.

I've kept various drains clean using all these methods for years in
varous crappo rented properties.

*shrug* If it works, use it.