The insurance under this policy is extended to include loss or damage to property insured directly caused by bursting or overflowing of water tanks, apparatus or pipes from within the building insured or containing the property insured, but excluding :
1. loss or damage whilst the building is unoccupied
2. loss or damage by water discharged or leaking from any automatic sprinkler installation in the within described buildings
3. the first ..... each and every loss
provided that all the conditions of the policy shall apply as if they had been incorporated herein and for the purpose of hereof any loss or damage as aforesaid shall be deemed to be loss or damage by fire.