Hi Tssk
There should be some "water wise" brochures available from the Council - if you have a PM (he/she) should be up on it and be one step ahead. However if you manage your own, get some literature to the tenants. Be positive in seeking their cooperation "for everone's benefit". Ask them to report any leaks immediately- toilet, taps etc (the restrictive shower head is good)and make sure they are quickly fixed. Up here the tenant is charged (if you wish) for "excess water", "excess" being over approx 1000 ltrs daily. Water restrictions probably exclude the use of sprinklers, however remind them that a sprinkler uses 1000 ltrs per hour - the entire daily allowance.
Good luck
Mitzi