High Efficiency shower heads often cost less than conventional shower heads so if you are already replacing a showerhead it will always make sense to use a high-efficiency model. This is because they are simpler.

In new construction, this makes high-efficiency shower heads pay off immediately. More expensive shower heads tend to have features that waste water. In retrofit, the payback period for replacing shower heads with high-efficiency units varies widely depending on:

1. The average number of users per shower head per day. High – efficiency units save more energy when installed in a busy gym or communal dormitory than when installed in a private residence 
2. The habits of the Bathers. The water consumption during each shower depends on the duration of the shower and the setting of the flow rate. This depends largely on whether the shower is used primarily for hygiene or as an aesthetic experience. 
3. The type of valve. Install User friendly shower valves. If the valve in the shower provides only full flow, the bather must adjust the spray at the shower head to modulate flow. Also, avoid On-Off valves.
   In principle, this valve avoids the need to adjust the main hot and cold water valves. Once the main valves are set properly, the water is simply turned off at the shower head. In reality, it does not speed the process of getting the desired water temperature in the shower. The stagnant water must still clear the line quickly. This type of shower head is also prone to causing leaky valves 
4.  The cost of water and water heating energy.
   High efficiency shower heads may worsen the problem of water temperature fluctuation. This problem occurs only if the cold water piping is too small, so that it cannot maintain water pressure when another fixture draws a large flow. In a well designed service water system, both the cold and the hot water piping is of ample diameter to serve all fixtures. A low flow shower head may make it less likely that use of other fixtures will cause temperature fluctuation in the shower since more hot water or cold water capacity is left over for other water-using devices.
5. The characteristics of the shower head. More energy will be saved if it is easy for bathers to use showers efficiently.
   If adjustable shower heads are installed, select a type that is easy to adjust, best example is the large butterfly knob on the side of the showerhead. Some cheap models have a knob in the center plate of the shower head – forcing the user to reach through the spray to adjust it.