WaStop Pulsating Flow

The Problem 

Maintenance budgets are tight. Reducing the maintenance requirements for sewer and stormwater networks is essential. Low-flow toilets and infrequent rainfall can lead to a build-up of debris in sewer pipes. Debris that needs to be removed by maintenance teams. Pipes can often be difficult to access and outfalls even more so depending upon the location.

The Solution  

WaStop inline check valves have a unique pulsating flow mechanism built into the membrane. The pulsating flow mechanism increases the velocity of the flow which flushes debris out keeping the pipes cleaner both upstream and downstream. This reduces the need for maintenance and therefore reduces costs.


Reducing maintenance requirements is an important feature of any product put into a storm or sewer system. Access is often difficult and can require confined space certification, or can be in areas where shoreline access is required. Having low maintenance requirements and a high reliability factor are key features of WaStop inline check valve. To ensure the product functions when required a pulsating mechanism has been engineered into the WaStop.

By keeping a small amount of water behind the valve, the debris upstream is kept fluidized which reduces sedimentation build-up in the pipe. A self-cleansing effect is achieved by building up pressure behind the WaStop prior to opening. When the valve opens the velocity of the water is higher than it would have been without a valve, or with a different type of check valve, thereby increasing the flushing effect. The effect can be likened to a toilet flushing.

The pulsating flow action minimizes the build-up of debris, and therefore minimizes maintenance.


To create the self-cleansing pulsating flow a certain amount of head pressure is required to open the WaStop.  The WaStop remains open until the pressure drops below the closing pressure of the valve. This creates a pulsating flow which helps keep pipes cleaner both upstream and downstream. Both the opening pressure and closing pressure are set valves for each valve and each type of membrane. In some instances it is desirable to have a higher opening pressure to gain a greater flushing effect, whilst in other applications a lower opening pressure is preferred. This can be discussed with your WaStop representative to find the perfect fit for your application.

Debris is able to exit the pipe through the WaStop, without compromising the seal. When closing the WaStop ‘snaps’ shut clearing out remaining debris and particles from the seat of the valve allowing a good seal.  Should an item fasten on the way though the valve the membrane is flexible enough to create a seal if backpressure occurs.  On the next pulsating flow cycle the item will be flushed through. 

At the point of opening the WaStop DN1000 is open approximately 125mm x 410mm.  Even with this flow there is sufficient area for bottles, cans, shoes and other items commonly found in storm and sewer drains to be flushed through.  A higher flow gives a greater opening area.  Please refer to the headloss charts included with the technical specifications for more information.

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Wapro designed the WaStop membrane to have pulsating flow. This feature is tested in a testing environment continually. Our customers are testament to the function with reports of low maintenance and automatic debris removal. 

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Pulsating Flow comparison with other check valves

Pulsating flow is unique to WaStop. No other valve on the market has a pulsating flow mechanism. A flap valve or duck bill which constantly releases any upstream water, or other valves with very low opening pressure, allow the water to drain out of the pipe, sometimes at very low flows, leaving behind solids and debris. If debris is caught in the valve, such as often the case with flap valves or duckbills, backflow can enter the pipe rendering the valve ineffective. Without any pressure differential a duckbill or flap valve will no close causing upstream flooding.

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User experience 

Many municipalities/councils confirm that the pulsating flow mechanism to the WaStop membrane saves time on maintenance and therefore money as well as giving peace of mind.  

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WaStop® Inline Check Valve

WaStop® Inline Check Valve

Product information

We at Wapro know that any solution for flood prevention, or odor control needs to function. Simply, effectively. That’s why, when we invented the WaStop inline check valve backflow preventer in 2000 we had one thought in mind. Instant automatic protection. Working on differential pressure the WaStop functions autonomously, without human interaction, without electricity, without constant maintenance – it just works.

WaStop is available to fit most types of pipes from NPS 3" to NPS 80" and is also available in an Access chamber for easy access from ground level.

WaStop inline check valve excels in many areas. WaStop exhibits the lowest headloss on the market, 100% backflow prevention and a unique pulsating flow that keeps pipes both upstream and downstream cleaner which reduces maintenance costs substantially.

Click below to read more about Headloss, Backflow, Pulsating Flow and Installation.

View Product information

Technical Information

We at Wapro know that there is a wide range of pipes available on the market, and that these pipes aren’t always perfect. We designed this seal to not only create the perfect fit, but also to ensure quick easy installation. Time is money.

For the residential market we have designed a range of valves for protecting memories. Please refer to the WaStop Residential pages for more information.

WaStop is also available in an Access Chamber. The Access chamber has a pre-installed WaStop valve. The WaStop module is removable from ground level for easy maintenance. Available in NPS 4", NPS 5" and NPS 6". Please refer to drawings for more information.

The following technical information relating to WaStop inline check valves can be found on the tabs below.

  • Drawings
  • Technical Specifications
  • Installation Instructions
  • Certifications
Wapro-Wastop-backflow-flood-protection-dimensions View Technical Information

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