All aboveground polyethylene rainwater storage tanks are manufactured using resins that meet FDA specifications to ensure safe storage of potable water. The black or dark green color limits light penetration which reduces the growth of water-borne algae. All RMS rainwater storage tanks are shipped with the appropriate fittings necessary to connect your rainwater harvesting components. RMS aboveground rainwater storage tanks range in size from 200 gallons to 12,000 gallons.