Brown/yellow water from bath mixer taps

[sairejayne]

We have recently (early this year) had a new combi boiler and bathroom fitted. Ever since, we have had brown/yellow bath water from both hot and cold tap (its a mixer) the first time each one is turned on for that day. This lasts for a few seconds and clears. I would have expected with new pipework for it to have run clear, but it hasn't yet after around 8 months.
We do not get this problem with any other taps or the shower. What could the cause be?
Could it be the taps? Boiler or pipework (pipework to bath taps in new as these were repositioned, but should be copper).
Thanks,
S.

[heathfield]

If it's only the bathwater that's affected, then whoever fitted your bath has used an iron or steel pipe, or tap adaptor fitting, when it should have been brass or copper. It's rusting, and discolouring the water. Get on to them and create a fuss.

[sairejayne]

Thanks, that's what we suspected, but plumber/installer says could be boiler or mixer taps - just wanted to check!