How to Power a Well Pump With a Generator: Step by Step Guide

How to Power a Well Pump With a Generator: Step by Step Guide

No matter what the reason is, there are times when you might be without power. It’s important to know before a power outage how big of a generator you need to operate household essentials. One of the most important things to operate at all times is the well pump for your house. To do this, you’ll need to know what size generator you need and how to use it with your well pump. 

To power a well pump with a generator, make sure that power is running from the generator to the pump and turn the generator on. You can operate a well pump with both a whole-house generator and a portable generator. The means of providing power from the generator to the well pump is different, but it’s possible either way. 

In this article, we’re going to look at some of the requirements for operating a well pump with a generator. We’ll also look at how to provide power from a whole-house stationary generator and a portable generator. 

If you’re looking to use a battery backup for your well pump, read this article.

How to Power a Well Pump With a Whole House Generator

A whole house generator, also known as a stationary generator, is one that gets professionally installed in case of power outages. Most of your essential appliances and electronics are powered by your whole house generator. Included among these electronics is your house’s well pump. 

During a power outage, you’re going to want to use the bathroom and have running water, which is why it’s important to have a working well pump. In order to power the well pump with your generator, here’s what needs to happen. 

  1. When your generator is installed, make sure that the well pump is one of the items included on the generator’s list of things to power. 
  2. The electrician that installs the generator will install a transfer switch and a subpanel. 
  3. The transfer switch is wired into the main panel on your house as well as the generator subpanel. 
  4. It will be up to you and your electrician as far as which circuit breakers will be activated by the generator. 
  5. As long as the breaker controlling your well pump is among the breakers in the generator subpanel, your generator will automatically turn it on when it turns on. 

How to Power a Well Pump With a Portable Generator

Powering a well pump with a portable generator is slightly trickier, but still possible. It’s also something that you can do yourself, rather than needing a professional to do it for you. 

  1. Make sure that the portable generator in question is large enough to operate your well pump. There are many different sizes and types of generators and well pumps. Making sure that yours are compatible in size is step one. 
  2. Once you know that your generator is large enough to handle your well pump, start the generator. 
  3. Your well pump is located inside your house but your generator should stay outside. Carbon monoxide fumes inside your home from a running generator can be deadly. 
  4. Newer well pumps should have a cord on the end of them that gets plugged into an outlet. Run an extension cord from the well pump inside to the generator outside your house. If your well pump doesn’t have a cord end, then you’ll need to install one to proceed. 
  5. If the generator is running and the well pump is turned in, then your job is complete and your well pump has power. 

Here are some of the best portable generators to power your well pump and get you through a power outage. 

Durostar Portable Generator
3,053 Reviews
Durostar Portable Generator
  • Plenty of Power – With 4,000 peak watts and 3,300 running watts, this...
  • Powerful Engine – The DuroStar 208cc OHV engine is a workhorse that...
  • Low Oil Shutoff – Protects your investment by automatically shutting the...
  • Power Panel – The power panel includes a selection of outlets for maximum...
  • Complies with Emissions Standards – All DuroStar generators are both...

Generac Portable Generator
3,304 Reviews
Generac Portable Generator
  • Portable Power Solution: Weighing 25% less than comparable models, the...
  • High Quality and Consistent Power: With TruePower Technology, this...
  • PowerRush Advance Technology: This portable open frame inverter generator...
  • Quieter Operation: This Generac generator operates at 50% less noise,...
  • Smart and Reliable: Benefit from USB outlets for convenient charging of...

Will a 4,000 Watt Generator Power a Well Pump? 

A 4,000-watt generator will power most sizes of well pumps, but not all. Because there are several different sized well pumps for different sized houses, it’s important to know how big yours is. Well pumps are measured in terms of horsepower or HP. Here’s a chart explaining how big of a generator you need for your pump. 

Size of Well Pump Starting Wattage of PumpRunning Wattage of Pump
⅓ Horsepower2,000 Watts 750 Watts 
½ Horsepower2,500 watts 1,000 watts
¾ Horsepower 4,000 watts 1,650 watts 
1 Horsepower 5,500 watts 2.200 watts 
1 ½ Horsepower 7,000 watts 2,700 watts 
2 Horsepower10,000 watts 3,900 watts 
3 Horsepower 13,000 watts 3,250 watts 
5 Horsepower 20,000 watts 7,750 watts 
7.5 Horsepower 25,000 watts 11,500 watts 
10 Horsepower 40,000 watts 15,500 watts 

As you can see, a 4,000-watt generator can operate a well pump that’s between the sizes of ⅓ HP to around 1 HP. While a 4,000-watt generator has enough power to run a 2 HP well pump, it doesn’t have near the starting power. It’s important to remember to factor in starting and running power when determining if your generator can power it or not. 

How Many Watt Generator do You Need to Run a Well Pump? 

Generators are sized according to the number of watts they can power. A 5,000-watt generator, for example, can power up to 5,000 watts of electricity at a time before it gets overloaded. Because there are so many different sizes and types of generators and well pumps, not all generators can power all well pumps. 

Most residential houses operate with a ⅓ HP to ¾ HP well pump. Only in rare occasions with extremely large houses do they require a pump larger than ¾ HP. If your well pump falls into this category, then use the table given above to determine how big of a generator you need for your well pump. 

It’s important to remember, however, that you’ll likely be running more appliances than just your well pump during a power outage. Essential things like your furnace, air conditioner, water heater, washer, dryer, stove, and household electronics all need to be factored in. Make sure that your generator is big enough to operate these things in addition to your well pump. 

FAQ’s About Powering a Well Pump With a Generator 

How do I figure out the size of my well pump? 

Your well pump should have an identification plate on it that lists the size. You might need to remove your pump and clean it off if the plate has gotten dirty. It should, however, list the horsepower and wattage requirements on the plate. 

How do I figure out the size of my generator? 

Much like the ID plate on your well pump lists the size, your generator should also have a sticker or plate saying how many watts it is. 

What happens if a generator gets overloaded? 

On newer generators, if it gets overloaded the generator will automatically turn off. It will likely start running harder the more power you put on it and eventually turn off when it can’t handle anymore. 

Final Thoughts 

As you can see, it’s entirely possible to power your well pump with a generator. The most important thing to keep in mind when doing this is that your generator is capable of supporting the starting and running power of your well pump. 

If you’re using a portable generator, make sure that you keep safety in mind and run an extension cord from the pump to the outside of your home. You should never have a generator running inside your home. Carbon monoxide from the fumes can cause serious illness or even death. Always keep safety as your number one priority when running your well pump with a generator.

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