Safety and Low Flow Showerheads

By Tim Kilbane

With the green movement on the rise, homeowners are overwhelmed with tips and advice on how to conserve water and energy. Replacing the standard (2.5 gallon per minute) showerhead a low flow showerhead (less than 2.5 gpm) is a frequently recommended way to “go green.” As a result, low flow showerheads have been evaluated and rated by reporters, consumer bloggers and the EPA’s WaterSense program, based on the showerhead’s performance. This information has been consumed by eco-friendly homeowners in hopes of getting guidance in their showerhead selection process.
Lost among the buzz about low flow showerhead attributes is information about shower valve compatibility. Surprisingly, an important factor in selecting the low flow showerhead that offers the best showering experience is something that can have a dramatic effect on the safety of your showering experience; the shower valve.

What’s behind the wall makes a difference

Behind the wall in every shower or tub/shower combination is a mixing valve that blends the hot and cold water. Recent plumbing codes require mixing valves installed in showers to be safety-type valves, which have a mechanism inside that compensates for pressure disturbances that cause changes in the outlet water temperature.

There are two types of safety valves installed in most showers, thermostatic valves and pressure balancing valves. Thermostatic valves react to temperature changes in the water that result from a disturbance in water pressure within the plumbing system. Pressure-balancing valves react instantly to the pressure disturbance within the plumbing system to maintain a safe, pre-selected water temperature.
If you have ever experienced the sudden change in water temperature when a toilet is flushed or a washing machine cycle begins, you have experienced thermal shock. Thermal shock is a safety concern for bathers, not only because it can result in scalding of the skin but also because, more commonly, the bather suffers slip and fall injuries as he or she reacts quickly to avoid the sudden change in temperature in the water flowing out of the showerhead.

Shower safety valves are designed to react and adjust to these disturbances in water pressure within the plumbing system and, consequently, they maintain safe water temperatures, providing bathers a comfortable and enjoyable shower. Furthermore, certified shower safety valves must adhere to a standard as set forth by the American Society of Sanitary Engineers, listed as ASSE 1016 – Automatic Valves for Individual Showers & Tub/Shower Combinations. Minimum test requirements within this standard mandate that a safety-type valve maintain the bather’s set outlet water temperature at a flow rate of 2.5 gpm.

How pressure-balancing valves support low flow showerheads

As previously stated, safety valves work properly with a standard 2.5 gpm showerhead because they have been mandated to do so by ASSE 1016. However, the same valve may not work properly in combination with a low flow showerhead at a flow rate lower than 2.5 gpm. This is important for the consumer to understand, because, if the valve is unable to accommodate a change in pressure as a result of the low flow showerhead, it may not be able to maintain safe bathing temperatures.
Until a standard is published for showerheads and valves operating at flow rates lower than 2.5 gpm, bathers need to understand the importance of the valve and showerhead compatibility. For the safest shower experience, consumers and installers should contact the valve manufacturer and verify that the flow rate of the showerhead is compatible with their shower valve.

Low flow in the future

Manufacturers are working with industry organizations and standards developers to prepare standards for the safety of low flow showerheads and valve performance. In the future, consumers will have a better guide for compatibility because manufacturers will publish in their literature and on their packaging the valve and showerhead flow rates.

So, regardless of the latest consumer report on low flow showerheads, knowing the type of valve that is behind the shower wall could have the biggest influence on a decision in selecting the safest water and energy conserving showerhead.

Tim Kilbane is the national sales manager of Symmons Industries.