Why is it when someone flushes the toilet surrounded by an dated house the shower marine turns cold?? ...

What size nouns conditioner should I seize?
Answers:    Possibly cause corroded gal pipes giving low pressure to the D hot water cistern when there is a greater constraint. A bit like heart disease
Things to try
1 restrict sea flow at the cistern by closing the associated tap or inserting a pressure spigot
2 is the main slap @ the meter turned on fully?
3 replace gal pipe with copper or plastic u will inevitability a plumber for this.
My case is the reverse when the toilet is flashed the shower get hot. Have excessive mains hose down pressure.
My solution was separate pressure valve on different water dash branches to isolate usage effects.
Hadseptic pumped 7 months ago,and up to date...
because you dont have a regulator surrounded by the shower, i get frozen too when someone uses the kitchen sink