Have you ever noticed your well pump turning on and off rapidly every time you run the faucet? This “short cycling” not only wastes energy but can burn out your pump motor prematurely. If you are looking to extend your equipment’s lifespan and ensure consistent water pressure, learning how to plumb two pressure tanks for a well might be the perfect solution for your home.
Adding a second tank is a common upgrade for households with high water demand or older systems that struggle to keep up. It increases your total drawdown capacity, meaning your pump runs less often and for longer, more efficient cycles. In this guide, we will walk you through the exact steps, necessary tools, and expert tips to get your dual-tank system running smoothly.
Why Add a Second Pressure Tank?
Before diving into the plumbing, it is crucial to understand why this modification is beneficial. A single pressure tank has a limited volume of air and water. When you use water, the pressure drops until it hits the “cut-in” point (usually 30 or 40 PSI), triggering the pump.
By adding a second tank, you effectively double (or significantly increase) the available stored water. This provides several key advantages:
- Reduced Pump Cycling: The pump runs fewer times per day, reducing wear and tear on the motor and switch.
- Extended Equipment Life: Less frequent starting and stopping means your pump and pressure switch last longer.
- Better Water Pressure Stability: Larger volume helps maintain steady pressure during peak usage times, like when two showers are running simultaneously.
- Backup Capacity: If one tank fails or needs maintenance, you still have some water storage capacity from the second tank.
According to industry standards, a well pump should not cycle more than 10–15 times per hour under normal usage. Exceeding this limit is a primary cause of premature pump failure.
Can You Connect Two Pressure Tanks Together?
Yes, you absolutely can. In fact, connecting multiple pressure tanks is a standard practice in larger residential or commercial well systems. The key is ensuring they are plumbed in parallel, not in series.
When plumbed in parallel, both tanks share the same pressure reading from the system. They fill and drain together, acting as a single, larger vessel. This setup is straightforward and does not require complex valves or controls, provided the piping is sized correctly.
Expert Tip: Ensure both tanks are rated for the same maximum pressure. Mixing a 100 PSI tank with a 150 PSI tank is safe, but pre-charging them correctly becomes critical for optimal performance.
Tools and Materials You Will Need
Gathering the right tools before you start ensures a smooth installation. Here is a checklist for your project:
- Second Pressure Tank: Ensure it matches your system’s voltage and pressure requirements.
- Pipe Fittings: T-fittings, unions, and nipples compatible with your existing pipe size (usually 1-inch or 1.25-inch).
- PTFE Tape (Teflon Tape): For sealing threaded connections.
- Pipe Wrenches: Two adjustable wrenches for tightening fittings.
- Air Gauge: To check and adjust the pre-charge pressure.
- Water Pressure Gauge: To monitor system pressure during testing.
- Check Valve: If not already present near the pump outlet.
- Shut-off Valves: Ball valves for each tank to allow future maintenance without draining the whole system.
Step-by-Step: How To Plumb Two Pressure Tanks For A Well
Follow these steps carefully to ensure a leak-free and efficient installation. Always turn off the power to your well pump at the breaker box before starting any work.
Step 1: Turn Off Power and Drain Pressure
Safety first. Switch off the circuit breaker for your well pump. Open a faucet in your house to relieve the water pressure in the lines. Wait until the water stops flowing completely.
Step 2: Locate the Ideal Connection Point
Identify where your current pressure tank connects to the main water line. The best place to add the second tank is as close to the first tank as possible, ideally on the same side of the check valve. This ensures both tanks see the same pressure dynamics.
Step 3: Install a T-Fitting
Cut the existing pipe between the check valve and the first pressure tank (if necessary) or use an existing port. Install a brass or PVC T-fitting. One end of the “T” goes to the pump/check valve, one to the original tank, and the new open end will go to your second tank.
- Use PTFE tape on all male threads.
- Tighten fittings securely but avoid over-tightening, which can crack plastic components.
Step 4: Pre-Charge the Second Tank
This step is critical and often overlooked. Before connecting the tank to the water system, you must set the air pre-charge.
- Check the label on your pressure switch for the “cut-in” pressure (e.g., 30 PSI).
- Using an air gauge, check the air pressure in the new tank’s Schrader valve (like a tire valve).
- Adjust the air pressure to 2 PSI below the cut-in pressure. For a 30/50 PSI switch, set the tank to 28 PSI. For a 40/60 PSI switch, set it to 38 PSI.
If the pre-charge is too high, the tank won’t fill with water. If it’s too low, the bladder may rupture.
Step 5: Connect the Second Tank
Attach a union and a shut-off ball valve to the inlet of the second tank. Connect this assembly to the open end of the T-fitting you installed in Step 3. The shut-off valve allows you to isolate the second tank for future service without shutting down the entire well system.
Step 6: Restore Power and Test
Close all faucets in the house. Turn the power back on to the well pump. The pump should kick on and begin filling both tanks. Watch the pressure gauge.
- Listen for leaks at the new fittings.
- Observe the pump cycle. It should run longer than before and shut off at the “cut-out” pressure (e.g., 50 or 60 PSI).
- Run a faucet and observe how long the pump stays off after you stop using water. It should stay off significantly longer than with a single tank.
Common Mistakes to Avoid
Even experienced DIYers can make errors. Here are the most frequent pitfalls:
| Mistake | Consequence | Solution |
|---|---|---|
| Incorrect Pre-Charge | Tank fills with too much water or no water. | Always set air pressure to 2 PSI below cut-in. |
| Plumbing in Series | Uneven pressure distribution. | Always plumb tanks in parallel using a T-fitting. |
| Ignoring Check Valve | Water flows back into the well. | Ensure a check valve is installed between the pump and tanks. |
| Undersized Piping | Restricted flow and pressure drop. | Use pipe diameter equal to or larger than the main line. |
For more detailed technical specifications on well system components, you can refer to Wikipedia’s article on Water Wells which provides a broad overview of global well infrastructure standards.
FAQ: Frequently Asked Questions
1. Do both pressure tanks need to be the same size?
No, they do not. You can combine a large tank with a smaller one. The total drawdown capacity will simply be the sum of both tanks. However, ensure both are rated for the same maximum working pressure.
2. Where should the second pressure tank be located?
Ideally, it should be located as close to the first tank and the pressure switch as possible. Long runs of pipe between tanks can cause slight pressure delays, though this is rarely an issue in residential setups. Keep it indoors or in a insulated enclosure if you live in a freezing climate.
3. How do I know if my pre-charge is correct?
With the water pressure drained to zero (faucet open), check the air pressure at the tank’s Schrader valve. It should read exactly 2 PSI below your pump’s cut-in setting. If water comes out of the air valve, the bladder is ruptured, and the tank needs replacement.
4. Can I add a third pressure tank?
Yes, you can add as many tanks as your space and budget allow. Each additional tank further reduces pump cycling. Just ensure your piping manifold is robust enough to handle the flow.
5. Does adding a second tank increase water pressure?
Not directly. It increases water volume and stability. Your maximum pressure is still determined by your pressure switch (e.g., 50 or 60 PSI). However, you will experience less pressure drop during heavy usage because there is more stored water available.
6. How often do I need to maintain two tanks?
Check the air pre-charge in both tanks once a year. Over time, air can permeate through the bladder, causing the pressure to drop. Regular checks ensure optimal performance.
Conclusion
Learning how to plumb two pressure tanks for a well is a smart investment for any homeowner relying on well water. By increasing your system’s storage capacity, you protect your expensive pump from premature failure and enjoy more consistent water pressure throughout your home.
Remember, the key to success lies in proper pre-charging and parallel plumbing. Take your time, double-check your connections, and test thoroughly. If you are unsure about any electrical components, consult a licensed well technician.
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