Most civil reactors are next to lakes or rivers so it seems like they should have plenty of water. Is it a matter of civil reactors using smaller[cheaper] plum

Most civil reactors are next to lakes or rivers so it seems like they should have plenty of water. Is it a matter of civil reactors using smaller[cheaper] plumbing and pumps? My intuition is that Naval reactors are built to be very responsive because that's useful for naval applications, but civil reactors aren't built like that because that ability has less relative value for civil reactors.