Install low flow showerheads
Low flow showerheads are now designed to provide an effective shower with much less water than an old showerhead (52% saving) or even than a new standard showerhead (20% saving).
Look for WaterSense® certified showerheads. Numerous versions are available at most hardware stores. If you’d like advice on how to change it yourself, check out page 37 of The CMHC Household Guide to Water Efficiency.