WaStop Backflow Protection

The Problem 

Backflow in storm and sewer networks cause extensive damage to infrastructure in cities and towns in coastal areas or areas close to a water course affected by seasonal high water levels. Water can damage buildings, roads, gardens and parks, and can even be a health risk.

The Solution  

Stopping backflow prevents flooding and damage. WaStop protects against backflow continuously, autonomously and seals 100% tight* even at low backflow pressure levels.


Backflow in storm and sewer networks cause extensive damage to infrastructure in cities and towns in coastal areas or areas close to a water course affected by seasonal high water levels. Water can damage buildings, roads, gardens and parks, and can even be a health risk.

Stopping backflow prevents flooding and damage. It is essential to be able to have complete faith in any backflow prevention device used in storm and sewer systems. A backflow device should be autonomous. There should never be reliance on human action to activate a backflow device as there is often risk involved during storm events.

WaStop functions autonomously protecting against backflow continuously.

Backflow testing according to CE 13564-1 is conducted on WaStop valves under DN200 as per test specification.

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Backflow Testing

We at Wapro stand behind our products. Testing to ensure they perform to the quality and standards we adhere to is part of our daily activity. WaStop DN80-DN200 are tested according to CE 13564-1. Valves over this size are not covered by any CE standard, but to provide peace of mind we conduct the same tests on valves over DN200. Wapro is also ISO 9001:2015 and ISO 14001:2015 certified.

WaStop is sealed and closed by default, which gives an airtight seal at zero pressure. When pressure increases the sealing surface of the membrane is forced against the inner surface of the valve body, which maintains the seal.

To test our valves thoroughly we also test to the point of failure. Failure occurs with the backpressure exceeds the intended pressure by over 30%. When this occurs the membrane elongates to the point of failure.

Wapro also tests valves with various types of debris normally found in stormwater or sewer applications. We have tested with rags, bottles and cans, and other solids. Tests prove that WaStop, with flushes away debris which prevents anything getting stuck under the valve which would leak during a backflow event. WaStop membrane is flexible and can seal around most debris enough to prevent backflow and then flushes clean during the next rainfall event.

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Backflow Comparison with Competitors

All backflow devices prevent backflow. Some more than others. WaStop protects 100%* against backflow. One question we are asked frequently is 'what happens when debris gets stuck'. The answer is two fold. Debris doesn't get stuck due to the pulsating action of the membrane. But if something did not make it out during a single flush, the membrane is flexible enough to seal around most debris and the valve will still protect against backflow.

If debris gets stuck in a flap valve there is a large open area for backflow to occur and pressure is unable to build up to flush the debris out. Similarly with a duckbill there is a risk of debris building up inside the valve as most duckbills retain no water behind the valve, rather the water trickles out leaving debris upstream or in the bill of the valve. When this occurs debris can be caught in the sealing point of the valve and deforms the valve allowing backflow to occur.

*see document ' Acceptable Seepage Rates WaStop DN200-1800mm for more information.

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User experience 

Stopping backflow is the main reason for installing non-return backflow valves. The valves are just expected to work. However, through experience we have learnt that not all check valves protect 100% against backflow. Through thorough testing we can show that WaStop protects 100% against backflow. Providing peace of mind.

Holding back the flood.

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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.

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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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