Water Feature Water Supply

Water Feature Water Supply

When creating a fountain, it is crucial to ensure that it has a reliable water supply system in order to provide a means of quick fill and replenishment (aka make-up).

In this article, I will cover these two main functions as well as important details for supporting items such as water quick fill/make-up station assemblies, dealing with dangerous incoming water pressure, excessive water hammer, and utility water for practical maintenance.

Water conditioning will also be covered, including water quality, backflow prevention, water metering, and pressure.

As you can see, an acceptable water supply system for your fountain consists of many facets that must be addressed. If these are ignored or overlooked, the chances of multiple equipment and maintenance issues will more than likely increase.

Means of Water Replenishment

A means of water replenishment or make-up due to evaporation, etc., is necessary for your water feature. While a common garden-type water hose might suffice for tiny fountains, automatic fill systems are preferable for most. To achieve this, there are electrical and mechanical automated fill systems.

The electronic system is more complex, including a water level sensor, an electrically activated fill valve, and a control unit, whereas the mechanical system utilizes a float valve.

Outdoor water features are subject to loss of water due to splash, high wind, leakage, etc., which are due to bad design and/or installation. For the sake of this water makeup example, we will be focusing on evaporation only.

How to Size Your Water Make-Up System

There are many variables that influence evaporation, such as:

• Temperature

• Humidity

• Wind

• Total water surface area exposed

Let us consider an operating water feature with various effects, 500 sf basin(s), 100% exposure, and a 90°F temperature. The average loss of water would be about 2 gallons per day*. Now consider an automatic water make-up system that adds water after a drop of 1/2 inch from the normal operating water level.

How many gallons will it take to make up/return to the normal operating water level?

Answer; multiply your total surface area (500 sf) by 7.48 (gal/cu ft), then divide by 24 to get the 156 gallons needed to make up or return to a normal operating water level.

How long will it take to make up that 156 gallons?  

A water supply at 50 psi through a 1/2-inch solenoid make-up valve should deliver 4 gpm, so 156 gal/4 = 39 minutes.

How often will the water make-up valve operate?

That would be 156 gal/2 gal per day loss = every 78 days.

You may ask why my water makeup kicks on much more frequently than that.

Keep in mind that the calcs above are for water loss due to only evaporation and do not account for bad design and/or installation, which can and often do increase the loss of water considerably more than evaporation alone. Also, these specs can vary from one manufacturer of valves to another.

*GPM Loss per day = (SF of Fountain/100)*0.00032)*2)*720

Means of Quick Filling

There are times, such as at the initial start-up and after cleaning or repairs, when the fountain must be filled from a dry state. This would be impractical with only an electrical make-up water fill system due to the low flow of a solenoid make-up valve, for instance, and potential damage to the solenoid valve from prolonged or sustained usage. However, water filling may be accomplished via a mechanical float valve at 50 psi, which can handle much more flow.

For this exercise, we will consider filling the entire water feature within 4 hours. Any longer than 4 hours can result in overflow and wasted water due to personnel going to lunch and simply forgetting about it. You may laugh, but this happens. Due to time restraints, many municipalities will quickly fill from a fire truck or nearby fire hydrant.

OK, back to our numbers, 500 SF x 7.48 gal/CF = about 3,740 gal/ft. If our fountain is 16in deep, that would be 3,740 gal x 1.33 feet = 4,974 gals of total volume. To achieve water fill within 4 hours, we simply divide our volume (4,974) by 240 minutes (4 hours) to get the 21 gpm minimum flow rate needed.

Now, 4,974 gallons are filled in 166 minutes, or 2.8 hours, by a 1/2" float valve operating at 50 psi and 30 gpm. Achieving this would require a float valve in the lower basin, which most architects would deem unsightly and therefore unacceptable. An option would be to install a wall niche to hide the float valve.

Most manufacturers that provide these wall niche assemblies are only able to incorporate a small float valve of up to ½” due to size limitations, so while this may be an option for smaller fountains, anything larger would require multiples or a quick-fill through a ball or gate valve into the fountain via dedicated piping or recirculated system piping.

Just a quick side note about float valves, not all are created equal! Quality and flow rates from one manufacturer to another vary greatly, so be careful and do your homework when it comes to float valves. Some are complete junk and/or not rated for much flow at all.

Friction Losses in Water Supply System

For those of you in the weeds of friction losses, the figures above account for much higher velocities than a recirculating pump system. Two totally separate animals or design parameters.

Water Fill Make-up Station Assembly

The common water fill/make-up station assembly takes care of not only the main two functions covered above but other functions as well. Read on.

This assembly is designed with primary quick-fill piping and a bypass for make-up, including a solenoid valve. The quick fill piping typically includes a ball or gate valve for on/off quick fill of the water feature and would have nearly the same performance as we see above with a float valve. However, keep in mind that oversizing does not hurt and that costs may be insignificant when dealing with sizes up to 1 inch, for instance. Check your costs and availability.

Also note that most water fill/make-up station assemblies are made of metallic piping (usually copper), Sch 80 PVC, or PEX in order to withstand the higher pressure. Again, water fill and make-up systems are not typically designed using the same design parameters (pressures and friction losses) as recirculating pump systems.

Straining

The incoming water supply to your fountain should be filtered and treated potable city water, however, often that’s not available or desired compared to repurposed water from heating and cooling condensate, rainwater collection, well water, or natural bodies of water. For this reason, I recommend an inline Y-strainer with an 80 mesh screen be installed on the incoming water supply.

Straining debris will be a real advantage against eventual valve clogging issues, especially with solenoid valves. All it takes is a small speck of sediment to render a typical solenoid valve useless. The clogged, non-functioning solenoid valve will then require disassembly, cleaning, and reassembly.

Best Pressure for Water Supply

Having a regulated pressure of 50 psi on the incoming water supply is recommended, as a pressure too high or too low can create issues with most valves and other equipment. I recall a float valve installation in a reservoir system that spewed water constantly. It was found that the incoming water supply was 120 psi!

How to regulate water pressure

Incoming water pressure is regulated by means of a pressure-reducing valve (PRV). A PRV will take an incoming pressure that is too high for the system (within their rating ceiling) and reduce it to a more acceptable level, such as the recommended 50 psi mentioned above.

Water Hammer on Water Supply System

What is "water hammering"?

One of the best definitions I have run across is from Grundfos - Water hammering is a pressure surge caused by a rapid change in flow velocity in the pipeline. This phenomenon is referred to as "water hammering" because the pressure surges are frequently accompanied by a noise that sounds as if the pipeline were being pounded with a hammer.

To further clarify, when a wide-open valve (such as a fill or water make-up valve) is suddenly closed, a water hammer can occur due to an abrupt change in velocity, as the Grundfos definition states above. Unchecked water hammer can cause issues with equipment and, ultimately, pipe bursts.

How to prevent water hammering

Water hammer can be prevented by installing a “slower closing” solenoid valve in addition to a water hammer arrestor. These are very common on quality water fill/make-up station assemblies from most manufacturers.

Utility Water

A utility water source is a very necessary convenience in a water feature system.

What is meant by “Utility Water”?

Utility water is simply access to pressurized water for rinsing debris from filter cartridges, priming pumps, cleaning the equipment room, testing/troubleshooting systems, safety washing, etc.

If you have ever been in an equipment room with no utility water, you know the challenges. You must haul buckets of water and/or carry a pressurized sprayer with you, which is not fun or practical for regular maintenance.

How to provide utility water

Utility water for a fountain is typically accomplished with a common hose bib included as part of the water fill/make-up assembly (on the incoming water side); otherwise, install a dedicated water line with an isolation valve for utility water access. A garden hose attached to the hose bib makes for easy and practical maintenance as well as the other functions mentioned above.

An alternative could be to attach a garden hose to the blow-off of the incoming water supply Y-strainer via a valve. A flexible hose would normally be attached to the blow-off anyway in order to periodically clean the strainer, if not hard piped to a sump or drain.

Prior Conditioning of Water Supply

Like “prior conditioning of electrical power supply,” I typically specify that “all prior conditioning of water supply” be provided and installed by the project G.C., not the water feature installer.

Water conditioning includes, but is not limited to, quality, pressure regulation, backflow prevention, and metering. The specifications change greatly from one governing jurisdiction to another, so much so that it is more practical for a local G.C. or city utility to provide as required.

Water Quality for Fountains

As stated above, referencing water sources Sometimes the only available or practical water supply is non-potable water. In this case, water filtration and disinfection should be done before it is introduced into the water feature.

Pressure Regulating for Water Features

On occasion, the municipal water supply may be operating at a pressure much higher than a standard PRV can handle. In this case, multiple PRVs or a more specialized commercial/industrial means of pressure reduction would be required.

Backflow Prevention for Fountains

Backflow prevention safeguards against potentially contaminated water getting back into the city water supply. As you can imagine, this could pose a health risk for all the users of the city's water supply, whom they trust.

Backflow prevention is usually required by the local governing jurisdiction. Most of the time, this means a backflow prevention assembly or, at the very least, an air gap installed on the water supply for your fountain.

Water Flow Monitoring System

Water flow metering is typically not required by the local governing jurisdiction vs a decision by the owner in order to monitor the fountain’s water consumption. This monitoring is useful to recognize issues such as leaks, etc. which otherwise would go unnoticed at locations using enormous amounts of water such as shopping centers. 

I hope this article has answered your questions or at least made you aware of the many facets of a needed water supply for your water feature! If you have more questions, please do not hesitate to contact me. I would love to help you.

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