Deputies vote to turn the quarry into the next reservoir while rubble and builders' waste will be dumped near the Longue Hougue reclamation.
Stone extraction at Les Vardes quarry on the west coast has stopped for now, as Ronez moves that work to Chouet.
But the firm is still using the quarry for crushing stone, so turning it into a reservoir is some years away.
Deputy Lindsay de Sausmarez told deputies they were voting for the long term provision of drinking water, but deputy Marc Leadbeater was unconvinced:
"There's certainly been no evidence we have a water storage crisis.
"We have a housing crisis, we admit that don't we, we know that.
"But we haven't had a hosepipe ban since I was a kid."
In a separate vote, following a successful amendment by deputy Mark Helyar, who also questioned the need for such storage capacity, inert waste will be dumped at Black Rock.
This is an area of the South Side of the Bridge, near to the northern end of Longue Hougue and its use here will help the regeneration of the Bridge by providing land.
In the meantime, rubble and builders waste will continue be stockpiled.
Guernsey gets behind community café after online appeal
Guernsey Waste warn of the fire hazard of disposable vapes
No rush to ban social media for the under-16s in Guernsey
Guernsey businesses encouraged to use the daily St Malo ferry for European imports
Guernsey's airline to drop its European holiday routes
A total ban on disposable vapes in Guernsey and Jersey is poised to take full effect
Guernsey's Air Display to remain an early evening event
Disgraced Guernsey politician and pastor jailed for 9 years
