How To Plumb Twin Pressure Tanks For A Well: The Ultimate Guide

Are you tired of hearing your well pump cycle on and off every time you flush a toilet or run the dishwasher? This frequent cycling, known as “short-cycling,” not only drives up your electricity bill but also drastically shortens the lifespan of your expensive submersible pump. If you are looking for a robust solution to stabilize your water pressure and increase your storage capacity, learning how to plumb twin pressure tanks for a well is the most effective upgrade you can make.

In this guide, we will walk you through the exact steps to connect two pressure tanks safely and efficiently. Whether you are adding a second tank to an existing system or building a new setup from scratch, this tutorial ensures you achieve optimal performance, better water flow, and peace of mind.

Why Use Two Pressure Tanks Instead of One?

Before diving into the plumbing specifics, it is crucial to understand why this configuration is superior for many households. A single pressure tank has limitations regarding drawdown capacity—the amount of water available between pump cycles.

The Benefits of Dual Tanks

• Reduced Pump Cycling: By doubling your air volume, you significantly increase the drawdown. This means your pump runs less frequently, reducing wear and tear.
• Consistent Water Pressure: Larger water volume buffers against pressure drops when multiple fixtures are used simultaneously (e.g., showering while doing laundry).
• Backup Redundancy: If one tank fails or needs maintenance, you can isolate it and still have partial water pressure from the second tank.

According to industry standards, extending the runtime of your pump motor by reducing cycles can double its operational life. This makes the initial investment in a second tank highly cost-effective over time.

Essential Tools and Materials Needed

To successfully plumb twin pressure tanks, you need the right equipment. Using high-quality materials prevents leaks and ensures longevity.

Checklist:

1. Two Pressure Tanks: Ensure they are rated for your system’s PSI (usually 40/60 or 50/70).
2. Stainless Steel Flex Connectors: These absorb vibration and prevent stress on pipes.
3. Brass Tee Fittings: For splitting the water line.
4. Ball Valves: One for each tank inlet/outlet to allow isolation for maintenance.
5. Teflon Tape & Pipe Dope: For sealing threaded connections.
6. Adjustable Wrenches & Pipe Cutters.
7. Air Compressor & Tire Gauge: For setting pre-charge air pressure.

Pro Tip: Always use brass or stainless steel fittings near the pressure switch and tanks. Avoid galvanized steel, which can corrode and contaminate your water supply.

Step-by-Step: How To Plumb Twin Pressure Tanks For A Well

Follow these steps carefully. Safety first: Always turn off the power to your well pump at the breaker box before starting any work.

Step 1: Determine the Configuration

There are two primary ways to connect twin tanks:

1. Parallel Connection (Recommended): Both tanks connect to the main water line via a tee fitting. This is the easiest method and provides balanced pressure.
2. Series Connection: Water flows through one tank into the next. This is rarely used for residential wells as it offers no significant advantage over parallel and complicates maintenance.

We will focus on the Parallel Connection as it is the industry standard for reliability.

Step 2: Set the Pre-Charge Air Pressure

This is the most critical step often overlooked by DIYers. The air pressure inside the tank must be set correctly before water enters the system.

• Check your pressure switch settings (e.g., 40/60 psi).
• Set the air pre-charge to 2 PSI below the cut-in pressure.
  • Example: If your pump turns on at 40 psi, set the tank air pressure to 38 psi.
• Use a tire gauge on the Schrader valve at the top of the tank. Adjust using an air compressor if necessary.
• Note: Both tanks must have the exact same pre-charge pressure.

Step 3: Install the Manifold (Tee Fitting)

Locate the main water line coming from your well pump. You will need to install a brass tee fitting into this line.

1. Cut the main pipe where you want to branch off to the second tank.
2. Install the tee fitting using appropriate adapters (threaded or soldered, depending on your pipe type: PEX, Copper, or PVC).
3. Ensure the flow direction aligns with the incoming water from the pump.

Step 4: Connect the First Tank

The first tank is usually already installed. If you are replacing it or installing both new:

1. Attach a ball valve to the inlet of the first tank. This allows you to shut off water to this specific tank later.
2. Connect a flexible stainless steel connector between the ball valve and the main tee fitting.
3. Tighten all connections securely, but do not overtighten, which can strip threads.

Step 5: Connect the Second Tank

Now, plumb the second tank in parallel with the first.

1. Install a ball valve on the inlet of the second tank.
2. Run a pipe from the other side of the main tee fitting to this ball valve.
3. Use another flexible connector between the ball valve and the tank.
4. Ensure the second tank is positioned on a level, stable surface. It does not need to be at the same height as the first, but keeping them close minimizes pipe length and heat loss.

Step 6: Check for Leaks and Re-Pressurize

1. Close both ball valves initially.
2. Turn the water supply back on slowly.
3. Open the ball valve for the first tank. Check all joints for leaks.
4. Open the ball valve for the second tank. Check for leaks again.
5. Once confirmed leak-free, restore power to the well pump.

Troubleshooting Common Issues

Even with careful installation, issues can arise. Here is how to address them:

For more detailed technical specifications on pressure tank mechanics, you can refer to the Wikipedia page on Hydraulic Accumulators, which explains the physics behind pressure storage in closed systems.

FAQ: Frequently Asked Questions

1. Can I mix different sizes of pressure tanks?

Yes, you can connect a 20-gallon tank with a 44-gallon tank. However, ensure both have the same pre-charge air pressure. The total drawdown will be the sum of both tanks’ capacities. Just note that the larger tank will handle the bulk of the water storage.

2. Do I need a check valve when adding a second tank?

If your well pump already has a check valve installed (which it should), you do not need additional check valves for the tanks. However, installing ball valves on each tank is highly recommended for isolation purposes.

3. How far apart can the two tanks be?

Ideally, keep them within 10–15 feet of each other to minimize pressure drop and pipe complexity. However, technically, they can be farther apart as long as the piping is sized correctly to maintain flow rate.

4. Will two tanks increase my water pressure?

No, tanks do not create pressure; the pump does. Tanks store pressurized water. Two tanks will provide more consistent pressure and longer run times between pump cycles, but they will not raise the maximum PSI beyond your pressure switch setting.

5. How often do I need to check the air pressure?

Check the air pressure in both tanks once a year. Over time, air can permeate through the bladder or leak from the valve stem, causing the tank to become “waterlogged.”

6. Is it better to have one large tank or two smaller ones?

Two smaller tanks often offer more flexibility in tight spaces and provide redundancy. If one fails, you still have water. However, one large tank may have slightly fewer connection points where leaks could occur. For most homeowners, the benefit of redundancy and easier handling of smaller tanks outweighs this.

Conclusion

Learning how to plumb twin pressure tanks for a well is a smart investment in your home’s infrastructure. By following this guide, you have taken a significant step toward eliminating annoying pump cycling, reducing energy costs, and ensuring a steady, reliable water supply for your family.

Remember, the key to success lies in setting the correct pre-charge air pressure and using quality fittings like ball valves and flex connectors. Don’t rush the process—take your time to check for leaks and verify your settings.

Did you find this guide helpful? Share it with your neighbors on Facebook or Pinterest who might be struggling with their well water systems. If you have any questions or unique setup challenges, leave a comment below—we’d love to help you troubleshoot!