As a plumbing expert with years of experience in the field, I've encountered a variety of issues that can cause a water heater to leak from the bottom. There are several potential causes for this, and I'll go through them in detail.

1. Corrosion and Rust: Over time, the metal of the water heater tank can corrode and rust, especially if it's exposed to hard water or if the water heater is old. This corrosion can lead to small holes or cracks in the tank, causing water to leak from the bottom.

2. Loose Drain Valve: As you mentioned, a loose drain valve is a common cause of leaks. The drain valve is typically located near the bottom of the tank and is used for draining the tank during maintenance or when replacing the water heater. If it's not tightened properly, it can allow water to seep out.

**3. Faulty Temperature and Pressure Relief Valve (T&P Valve)**: The T&P valve is a safety device designed to release water from the tank if the temperature or pressure inside it becomes too high. If this valve is faulty or not functioning correctly, it can cause water to leak from the bottom.

4. Damaged Internal Components: Inside the water heater, there are various components such as the heating element or burner, which can become damaged over time. If these components fail, they can cause water to leak from the bottom of the tank.

5. Cracked or Damaged Tank: The tank itself can develop cracks or become damaged due to thermal stress or manufacturing defects. This can lead to water leaking from the bottom of the tank.

6. Loose Connections: Other than the drain valve, there are several other connections and fittings in the water heater that can become loose over time. These include the connections for the cold water inlet, hot water outlet, and any auxiliary components.

7. Sediment Buildup: Over time, sediment can build up in the tank, which can cause damage to the tank's lining and lead to leaks.

8. Improper Installation: If the water heater was not installed correctly, it can lead to various issues, including leaks from the bottom.

9. Thermal Expansion: When water is heated, it expands. If the water heater doesn't have adequate expansion space or if the pressure relief valve is not functioning correctly, it can cause water to leak from the bottom.

10. Sealant or Gasket Failure: There are various seals and gaskets within the water heater that can fail over time, leading to leaks.

To address a leak from the bottom of a water heater, it's important to first identify the source of the leak. This can be done by visually inspecting the area and looking for signs of water. Once the source is identified, the appropriate repair or replacement can be carried out. In some cases, it may be more cost-effective to replace the water heater rather than repair it, especially if it's old or has multiple issues.

It's crucial to address leaks promptly, as they can lead to water damage and potential safety hazards. Regular maintenance and inspections can help prevent these issues and extend the life of the water heater.

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Cause #2: A leak from the drain valve. Every water heater has a drain valve at the bottom of the tank. The drain valve is used when draining the tank to remove sediment that builds up and eventually causes damage to the inside of your tank. ... Replacing the drain valve will usually solve the problem.read more >>