From the MX, Monday 5 June 2006, p.7:

It could be possible - "hard" water has more minerals in it (or is that "soft" water) and as a result, these minerals can build up on things, and cause blockages. It happens over here as well - gunking up pipes and stuffing up hot water services.

Just had to respond to this one

Rail Company spokesmen/women are very good at shooting themselves in the foot over here, but there is actually some truth in this one! What I can't figure out is why no one bothered to think about this in advace Everyone knows the water in the South of England is generally very hard and chalky. Your kettle furs up with scale very quickly and a cup of tea generally comes complete with a horrid scum on top. In steam days, water treatment was a tremendous problem in a lot of Southern England as a lot of the water comes from aquifers in the chalky downs (which are now nearly empty, hence being told there is a "drought" on when it has done nothing but rain for most of this year!). You can imagine what our hard water does to locomotive boilers.

OVS Bulleid (there's that man again!) sought to overcome this problem by adopting the TIA (Traitement Integrale Armand) water treatment system that he had studied and which was used by the SNCF in France. You can see this in the group of cylinders that appeared on the top rear of the tenders of his Pacifics on the Southern (and the notification coded on cabsides of the locomotives).

Looks like so-called "Southern" who run the London-Brighton services had better do a bit more reading about the work of their predecessors on the real Southern Railway.

21C123 is right on the money here

Previous generations of SR stock had track-discharge toilets, some of which were literally an open downpipe to the ballast while others had a basic flap (like port-a-dunnies around the world) so you wouldn't see the sleepers rushing past while you dealt with natures call.

Since BR days conventional flush lavatories have been used but still with track discharge until the advent of class 319 Thameslink and 442 Wessex units from which time retention toilets were fitted.

Southern England has some of the hardest water in the world and as 21C123 has described it perfectly I need not repeat that. Reports suggest that the current class 377 family, which has a different design of toilet system, are being found incapable of dealing with the sediment this water causes, and the toilets are blocking.

From my travels on these sets I can confirm that the toilets are too frequently out of service and can produce a foul smell in the adjacent seatign area of the saloon. But it would be typical of the operator to take urgent action to address the problem and this would likely be an ongoing modification programe.

We can only wait and see what relief (sic!) can be achieved from this problem