Flap Valve, Penstock & Flow Control FAQs

A non-return valve lets water flow out of a pipe and stops it flowing back in. Also called a check valve or backflow valve, it protects drainage from rivers in flood, high tides and surcharged sewers. The three main types are flap valves, duckbill valves and inline valves such as the WaStop®.

A flap valve uses a hinged flap over the pipe end, a duckbill uses rubber lips that press together, and a WaStop® uses a flexible membrane inside the pipe. Flap valves are robust and suit most outfalls, especially large ones. A WaStop® suits pipes with no headwall, vertical pipes and sites where odour is a problem. Compare our flap valves and WaStop® valves.

Use a pipe-mounted flap valve or a WaStop® inline non-return valve. A pipe-mounted flap valve fits into the end of the pipe. A WaStop® fits inside the pipe, at the end or between two pipes, at any angle.

The WaStop® is an inline non-return (check) valve made by Wapro that stops backflow, flooding and sewer odour with no moving parts and no power. AQUIKO is the UK’s sole importer of the WaStop®. See the WaStop® range.

A flexible membrane opens under normal flow and closes when flow stops or reverses. It works on differential pressure alone, with no electricity, floats or hinges. When closed it seals tight against backflow and keeps sewer odours and rodents out of the pipe. How the WaStop® works.

The WaStop® opens at a low head, so it loses less head than a flap valve or duckbill of the same bore. A 215mm WaStop® gives the same head loss as a typical duckbill of 300mm or more. Wapro publishes opening and closing pressures for every size. Ask us for the data for your pipe size.

A flap valve is a non-return valve fitted to the end of a pipe or an outfall wall. Outflowing water pushes the hinged flap open; when the water outside rises above the level in the pipe, the flap is pushed shut and stops water flowing back up the drain. See our flap valves.

A tidal flap valve closes as the tide rises and opens again as it falls. Outside water pressure holds the flap shut against its seat; as the tide drops, water building up in the pipe pushes the flap open and the pipe discharges.

UV-stable HDPE is light, doesn’t corrode in sea water or sewage, and opens at a lower head than iron. It also has little scrap value, so it isn’t a target for metal theft. Stainless steel is available for bespoke designs.

Our standard round HDPE flap valves come in sizes from 100mm to 1500mm. Anything larger is made to order as a custom flap valve. Square flap valves suit box culverts and chambers.

Only for a wall-mounted flap valve. If there is no wall, use a pipe-mounted flap valve. We also supply precast headwalls with a matching flap valve.

In drainage and flood defence, a penstock is a gate that slides across an opening to stop, isolate or control the flow of water. It sits in a frame on a wall, channel or pipe, and is opened with a hand wheel, key or actuator. See our penstocks.

The two terms are often used for the same thing: a gate that controls water flow through an opening. In UK drainage, “penstock” usually means a standard gate in a frame on a wall, channel or pipe.

The main types are wall-mounted, channel, flush invert, inline, weir and flood defence penstocks, plus compact hand stops. Each suits a different job, from isolating attenuation tanks to holding back water through flood walls.

Our standard wall-mounted penstocks are rated up to 6 metres water column (m w.c.), and lightweight models up to 3 m w.c. Flood defence penstocks are rated at a minimum of 6 m w.c.

HDPE suits most UK drainage: it is light, corrosion-resistant and low maintenance. Choose stainless steel 316 for aggressive environments or where extra strength is needed.

By turning a spindle with a hand wheel or key, or with an electric actuator for remote or automated control. We supply hand wheels, spindle extensions and actuators.

Stop logs are removable barrier sections that slot into a frame to isolate flow, allow maintenance or act as a weir. AQUIKO stop logs are aluminium, in stainless steel 316 frames with integral seals. See our stop logs.

A tilting weir is a gate that pivots rather than slides to set and hold an upstream water level. Water spills over the top, and tilting it raises or lowers the level. We make them in HDPE or stainless steel 316L, operated manually or automatically. See our tilting weirs.

An orifice plate restricts flow to a set rate, for example limiting discharge from an attenuation tank. AQUIKO orifice plates are HDPE, sized to your flow rate, from DN100 to DN600. See our orifice plates.

Our penstocks, flap valves, stop logs, tilting weirs and orifice plates are designed and made in the UK. The WaStop® is made by Wapro and imported by AQUIKO.

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Yes. Custom flap valves, penstocks, stop logs, tilting weirs, orifice plates and WaStop® valves are made to order. Send us your sizes, drawings or flow requirements.

Yes. We supply both, with standard sizes held in stock and technical support on drawings, specification and installation.

Yes, we deliver UK-wide.