What you have spoken is TRUE!Tenents must have the responsibility to handover the house clean and to repair the broken fittings.Preparing written agreements with many clauses to safeguard the property is a must!waterproofing the toilet floor before filling surki is mandatory.Tile gaps should be filled with waterproofing materials(epoxy) to prevent water seepage.All workmen must be responsible and supervision also required during importatant stages of construction.Don't lose heart!change the wiring .make it external.waterproof the tile gaps with epoxy.Dr fixit.Dont rent the house for students .Family is better.House is a good investment.Maintain the house and give it for a higher rent ,with proper agreement.