Rheem water heater warranties typically cover the tank for 6 to 12 years depending on the model. Parts warranties usually last 1 to 2 years. Professional series models offer longer coverage up to 12 years on the tank. Registration within 90 days of installation is often required for full warranty coverage. Keep your purchase receipt and installation records. Warranty claims require proof of proper installation by a licensed professional. Tankless models may offer longer warranties.