Home / Blocked internal drainpipes -stains on walls and smells Blocked internal drainpipes -stains on walls and smells Share this page Facebook Twitter Leaks from sink and bath waste - stains tend to appear slowly See also Drainpipes Get updates by email Subscribe to our monthly newsletter to receive actionable information on tenement management, maintenance, and energy efficiency. My interest is as an: Owner-occupier Landlord Technical / Professional Property Manager Other