Tenant's Responsibility: Tenants are usually responsible for maintaining or repairing any drains inside the boundaries of their property. This includes not pouring items down the sink that could cause the drains to block. If a drain becomes blocked through tenant misuse, then the tenant may be liable for the repair bill.

Landlord's Responsibility: The Landlord and Tenant Act 1985 states that it is the landlord’s responsibility to maintain their drainage, pipes, and other areas of plumbing. If the blockage is found to originate from an inside drain and caused by tenant misuse, the landlord should be able to pass this cost onto the tenant. However, if the blockage is due to wear and tear or structural damage, landlords are responsible for the drainage within the boundary of their property.

Water Company's Responsibility: The sewerage company is responsible for lateral drains, which are usually outside of property boundaries, and sewers. You don't have to maintain or repair lateral drains that you share with your neighbour.

It's important to note that these are general guidelines and the specifics may vary.