My boiler is currently plumbed to my house soft water supply. I have access to the raw water, which is quite hard - calcium hardness of 150ppm or so as I recall. I've heard conflicting opinions about which is better for the boiler. I am about to break into the manifolds again, so this would be a good time to replumb the supply if raw water is better for the system. I have the same question about storage, since I will soon be filling my tank with 800 gallons and again, I can use either raw or softened water.