In reply to Birks:
Your Landlord is is breach of Sect 11 of the Landlord and Tenant Acts.
https://www.citizensadvice.org.uk/housing/repairs-in-rented-housing/disrepa...
He is responsible for carrying out repair to the water pipework and he cannot put the rent up or try and recoup the costs of repair from you by any other means.
If he doesn't sort this out immediately inform him, in writing, that you are taking the matter to a solicitor and that you will hold him responsible for any legal fees you may incur.
If this doesn't work, get legal advice.
Confirm everything relating to this matter in writing to the Landlord.
Do not be tempted to withhold rent without getting legal advice
Post edited at 16:40