Instant hot water systems that are installed after a house is built use the cold water pipes to return hot water back to the water heater, or discharge that water through normal cold water use. (I imagine that systems that are installed during construction often have a dedicated hot-water return pipe.) This means that sediments from the hot-water pipes, generally contributed by the anti-corrosion rod, finds their way into the cold water system. This suggests that if you've installed one of these, you should be extra diligent about occasionally draining the water heater until the water runs clear. OTOH, it seems that normal cold-water usage ought to keep it fairly free of sediments, anyway. So which is true? Should you just drain the water heater occasionally as always, or more often?