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Welcome to our page, where we provide answers to recurrent questions. Please do feel free to contact us if you can’t find what you’re looking for.

A throttle, like vortex regulators, only releases a dimensioned flow at a specific pressure head. Compared with vortex regulators, the opening will be smaller for the same dimensioning flow, thus a throttle is prone to blocking, and requires more maintenance. Evacuation of water will be less efficient than use of a vortex regulator, and especially compared with WaReg, which features a constant flow and the biggest outlet area of the three.

WaReg is a constant flow regulator, which means that as soon as the pressure head has been reached WaReg will release the dimensioned flow. The vortex regulator, however, is set to release the dimensioned flow at a specific height, and will release less than the dimensioned flow in the event of a lower pressure. The WaReg’s constant flow optimises the need for water storage and evacuation of water from a capture base etc.

No, we instead suggest an upstream chamber when overflow is required. The level of a WaReg is constant.

Yes, the flow can be adjusted following installation. A new flow measurement will then be required, to find the precise flow. If at the time of ordering you know you will need to make adjustments, please inform us, and we will test for these flows and send instructions on how to achieve the desired flow.

WaBack is a normally open non-return valve, which means opening it doesn’t require any pressure. It is advantageous in low-lying areas, where the pressure head is minimal. WaStop, on the other hand, is a normally closed non-return valve, which means it closes even in the event of a positive upstream pressure, providing the advantage of being really one-sided. The disadvantage is that opening it calls for a certain opening pressure.

WaBack is an extremely reliable product that has been installed since the mid-1980s and has been used successfully all over the world. WaBack will protect your property day in day out for more than 20 years.

Most WaBack models are in stock in Europe and can be delivered immediately. In the US it takes 2-6 weeks, depending on the size of the WaBack.

Yes, WaBack has a loop on top of the float. The float can be lifted using this loop, and it can also be attached so it closes temporarily. If a permanent solution is required, such a solution can be purchased through us. Please contact us for further information.

As WaBack is a "normally open" valve, the maintenance requirement is minimal. After a backflow event we recommend rinsing and cleaning with an ordinary water hose.

All models of WaBack Standard have been designed to fit PP DN600, DN425 and DN1000 riser pipes.

Yes, WaBack is supplied complete, in a chamber with a back-trap and a sealing ring. Other accessories such as risers and covers should be ordered separately, depending on the customer's requirements.

The advantage is that it provides you with straightforward access from ground level, where you can easily do an inspection by lifting the lid and pulling up the WaBack module. It is supplied complete with an inspection chamber and non-return valve in one, and it has an open flow under normal conditions and closes as soon as there is any backflow. WaBack Access withstands 5 metres of back pressure, is reliable and has been used for more than 20 years.

WaBack Access is to be used for outdoor installation and WaBack Residential for indoor installation. Both non-return valves are easy to install, require minimal maintenance and provide 100% protection against backflow.

There are a number of solutions regarding backflow. It is thus important to draw up a list of all the ownership cost items before investing. This is to facilitate understanding of the consequences of the purchase decision over time. Important costs and factors: 

  • installation cost
  • maintenance cost
  • expected life 
  • operational efficiency
  • replacement cost
  • cost of consumed product


The cost of ownership for WaStop is low. This is because of a number of different factors such as the valve’s long life, quick and straightforward installation and low maintenance requirements.

It is not possible to say precisely how long installation takes. But installation will normally take about 30-60 minutes. Installing WaStop is usually a very simple matter requiring few tools and a minimum of effort. Many people can install WaStop valves themselves without needing to contact an external contractor. There are non-return valves that cost less than WaStop in terms of the purchase price but that are harder to install, leading to a high total cost for the valve.

To reduce the risk of debris build-up in the pipes, resulting in expensive maintenance measures, WaStop non-return valves feature a unique pulsating flow thanks to the design of the diaphragm and an opening pressure that ensures that the membrane opens enough to let debris through.

Yes, WaStop causes the lowest pressure loss of all the available non-return valves on the market. A pipe system works using pressure differences. When the upstream pressure is higher than the downstream pressure, this allows flow in the correct direction. Anything added to a system subsequent to the original installation/design will change the resistance in the pipes. Use of the WaStop non-return valve will slightly limit the system, but the pressure loss will be less than with any of the other non-return valves available.

The most popular sizes – 4" to 36" – can usually be delivered within 5 to 7 days. For custom end fittings and valves with a short body the delivery time is 30 to 45 days. 


Your choice depends on the internal diameter of the existing pipe, and on other dimensions such as the chamber size and the descent diameter. We will be happy to help you choose if you so wish. Please feel free to contact us.

Select the largest possible size, to minimise restriction within the pipe. For oval or round pipes, the minimum dimensions dictate which WaStop should be used.

Depending on the desired dimensions of the membrane, the materials silicone MVQ, EPDM and polyurethane are available. For some dimensions there are several hardnesses. The soft ones are used when the opening pressure is critical, and the hard ones when additional back pressure is necessary. For the standard membrane, all the properties are balanced to provide WaStop with the best conditions for most applications.

Yes, we can customise the WaStop, giving it one collar instead of two, to reduce the OD on the inlet side whilst the valve remains suitable for 5MwC back pressure.

Yes, WaStop can be fitted with an elliptical flange for fitting to the outlet, or can be adapted for fitting inside the pipe.

Yes, WaStop is designed to work with several different types of pipe. With its tapering gasket and unique design, WaStop can be used in a number of different pipes, e.g. RCP, PVC, PE, HDPE, VCP, corrugated metal pipe, cast-iron pipe. If your pipe has been lined or is special, please contact us for advice.

WaStop has been designed with a safety factor of 1.2. If the pressure exceeds this, then the membrane material in the WaStop will be stretched to fatigue point.

Yes – there are no problems. WaStop can be adapted to different installations. Contact us for further information.

Yes, WaStop is often installed in existing infrastructure, and is frequently used when other installations for prevention of backflow have not worked. WaStop is fitted inside the existing pipe and is bolted to the building or the actual pipe. No other intervention is needed.

Yes, WaStop seals tightly and effectively stops airflows, thereby preventing unpleasant smells through the sewers.

The membrane offering the highest resistance is hard, and can withstand 8m (26´) resistance. Our standard membrane withstands 5m (16´) resistance, and our soft membrane withstands 3m (12´) resistance.

WaStop is available in 304 stainless steel and 316 stainless steel. We recommend 316 for salt water and when there are high levels of hydrogen sulfide (H2S).

WaStop has been available on the market since 2000. Since then the product has been sold to 49 countries.

Yes, WaStop is used in sewers frequently and advantageously. This is to prevent backflow and unpleasant smells.

Yes, WaStop does work in salt water. The product has been successfully used in saltwater environments since 2002. For saltwater environments and environments with high levels of hydrogen sulphide (H2S) the material acid-resistant steel EN1.4404 / AISI 316 is recommended.

Stock items (DN75-1000) are delivered immediately. Special orders are delivered within 4-6 weeks.

WaStop is an extremely reliable product for dealing with backflow and flooding. The product has been manufactured since 2000, and has been successfully installed in several different types of environment worldwide. Thanks to the fact that WaStop is autonomous and no human intervention is required to activate a return-flow unit, WaStop also works without any problems in difficult weather conditions such as storms. I.e. when it’s extremely important that you can rely on the product.

About 20 years, depending on the location of the installation.

Yes, WaStop is excellent at stopping sand getting in. If you’re experiencing major problems with sand in your pipe(s), a solution involving several small WaStops is recommended. The flow will then be released more frequently and sand will be kept away.

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