MP Smith Syphon Diaphragm Washer SU9939

SKU DEC-063552

EAN: 5019923199390

£1.54

inc VAT£1.28 ex VAT

Lead time: 2-10 working days

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Description

Product Overview

The MP Smith Syphon Diaphragm Washer SU9939 is a replacement diaphragm seal designed for toilet cistern syphon mechanisms. It helps restore a dependable flush and can reduce common issues such as leaking or weak flushing caused by a worn washer. Ideal for quick, cost-effective maintenance without replacing the whole syphon.

Key Features

Direct replacement part – designed for SU9939 applications to help ensure a proper fit and reliable performance.
Improves flush performance – restores effective sealing to support a stronger, more consistent flush action.
Helps prevent leaks – replaces worn diaphragms that can cause water loss and ongoing cistern refilling.
Cost-effective repair – extends the life of your existing cistern syphon, avoiding unnecessary full unit replacement.

Use Case / Application

Suitable for plumbing maintenance and repair work on toilet cisterns where a syphon diaphragm washer is fitted. Commonly used in:

Domestic bathrooms and downstairs toilets
Rental property maintenance and routine plumbing call-outs
Commercial washrooms requiring quick, low-cost repairs
DIY replacement of a cistern washer to address flushing or sealing issues

Problem to Solution

Perfect for fixing a leaking or unreliable toilet flush where the existing syphon diaphragm washer has perished or lost its seal.

Product Specifications

• Manufacturer – MP Smith
• Manufacturer Part Number (MPN) – SU9939
• EAN / Barcode – 5019923199390
• Product Type – Syphon diaphragm washer (toilet cistern syphon seal)

Why Buy from BHL

MP Smith parts are known for dependable plumbing spares that help keep toilets and cistern systems working as they should. Order the MP Smith Syphon Diaphragm Washer SU9939 from BHL for competitive pricing, genuine replacement parts and free* & fast UK delivery. BHL are a specialist online merchant trusted by thousands of satisfied customers online since 1998, with thousands of 5 star reviews. Your order is delivered with care from UK warehouses. *see our terms

Reviews

Buying guide: Toilet Spares & Parts

Toilet spares keep a WC cistern filling, flushing and shutting off as it should. This category covers fill valves (also called float valves or ball valves), flush valves and siphons, push buttons and levers, flush pipes, cistern service packs, tap connectors with isolating valves, and support frames for wall-hung pans, basins and bidets.

Fill valves

The fill valve lets water into the cistern and closes when it reaches the set level. Start by checking where the supply enters: bottom entry valves rise from the base of the cistern, while side entry valves fit through the side wall. Then match the shank size, usually 1/2 inch with 3/8 inch on some cisterns, and choose a plastic or brass shank. Many bottom entry valves adjust in height to suit different cisterns. A servicing valve on the supply pipe next to the cistern lets you isolate it for repairs.

Flush valves, siphons and buttons

Flush valves: lift to release water and are worked by a lever, a cable from a push button, or air from a pneumatic button, which is common on concealed cisterns.
Siphons: the traditional alternative, worked by a lever or a push button.
Buttons and levers: match the operating type and the size of the hole in the lid or cistern front.

In England and Wales, under the Water Supply (Water Fittings) Regulations 1999, a WC flush must not exceed 6 litres, the smaller flush on a dual flush must be no more than two-thirds of the full flush, and the cistern needs a warning pipe or an equally effective overflow arrangement.

Finding the right part

Note any make or model marked inside the cistern, measure the old part and compare it before buying. For complete units, see toilets; for isolating and servicing valves, see valves.

Shop all Toilet Spares & Parts