On 2020-07-01, Andrew wrote:

On 01/07/2020 15:06, John wrote:
The best advice I have ever followed was to ditch bar soap and only use
liguid soap.


Then you are adding to the global problem of single use plastic :-(

Depends on what the bar soap is wrapped in!

I find the idea strange that solid soap, once dissolved in water &
rinsed down the drain with more warm water, is going to precipitate in
the pipes.


Surely the problem is people running washing machines at low temp ?.
In the 'good old days', washes were done at ~60 C so the drains got
a regular hot flush of water and detergent.

I use 60°C or higher about once a week, but I wash most outer clothes
at low temperatures because they last longer that way.


If all else fails and you have an external hopper or gulley then
sodium hydroxide is quite effective (with eye protction and old
clothes).

A bit of slime (not much) appeared again a couple of days ago; from
the way it's positioned I'm almost certain it's come from the bathroom
hopper (so nothing to do with laundry). I've run some sodium
hydroxide through the shower drain.