Smelly cold water.

[Humph]

Hi all, i had a new bath sweet fitted just over 12 months ago and up untill now everything has been fine.
However i recently noticed a bad smell coming from the cold water in sink. Hot and cold run out of same tap,i think its called a monoblock, and all is ok when running hot water but when you turn on cold water the smell hits you,its like a stale rotten smell. if you leave tap running smell disappears after about 30 secs to a minute.
There is now discolour or bad taste just smell. Whats confusing is my bath is next to the sink but theres no smell from cold water there, but bath taps are seperate.
Could it be the the sink tap ?? i have a combi boiler if this helps..

 

[Bahco]

Is this tap supplied from a tank in the loft

If so , check its state.

 

[75pete]

Does the supply for the sink and bath come off the cold header tank? or is the bath off the mains?
If sink is off the header tank .......check your tank for a dead bird etc.

 

[Humph]

sink and bath water coming from same feed and i believe they are mains fed. No stored water or tanks anywhere, just combi boiler in airing cupboard. The bathroom sink is probably the closest to boiler but as i said its only cold water so surely this is coming straight from main supply ??

 

[TicklyT]

It wouldn't be the first time a cold water storage tank has been left in a loft providing cold water for the bath when a combi boiler has been installed.

 

[Humph]

Definatley no cold water storage tank in loft, or anywhere else in house.

 

[HarrogateGas]

Is the tap connected with flexi hoses?

 

[Humph]

Yes mate, 2 copper pipes coming up from floor that change to flexi house, about 12 inch long each. they then change back to smaller copper pipes as they approach underneath of basin.