The connection to a plastic storage cistern uses a flanged tank connector and which type of washers?

• A. Plastic and rubber washers
• B. Metal washers
• C. Rubber-only washers
• D. No washers

Answer: (A)

When connecting a flanged tank connector to a plastic cistern, the seal needs to be both durable and gentle on the plastic. A plastic washer against the cistern flange provides a firm, non-damaging seating surface that helps distribute the clamping load so the plastic doesn’t crack or distort. A rubber washer sits under the nut or against the threaded part to compress and fill small gaps, creating a reliable watertight seal that can accommodate minor irregularities and movement. Relying on metal washers risks corrosion or marring the plastic; rubber alone may creep and fail to distribute load evenly; and having no washers would leave gaps and leaks. Using both plastic and rubber washers together gives the best balance of protection and sealing for a plastic cistern connection.