Water Softener Wattage for Generator Sizing
About the Water Softener
A whole-house water softener system with a control valve motor and timer. Water softeners draw very little power during normal operation, with the control valve motor only activating during regeneration cycles. The starting surge is minimal. While not essential during short outages, homes with very hard water may want to include the water softener in generator sizing for extended outages to prevent scale buildup in pipes and water heaters.
Generator Sizing for a Water Softener
Running a water softener by itself requires a generator with at least 125 W of capacity (1 kW), which includes a 25% safety margin. However, you rarely run a single appliance on a generator. When combined with other appliances, the water softener contributes 50 W to the continuous running load and adds a potential 50 W starting surge gap when its motor starts.
The water softener is an inductive (motor-driven) load with a starting surge of 100 W, which is 2.0 times its running wattage. This starting surge occurs for a fraction of a second when the motor first engages and must overcome inertia to begin rotating. Your generator must be capable of delivering this peak wattage even though it only lasts briefly. If the water softener has the largest starting surge gap of any appliance in your generator load, its surge gap of 50 W will be the primary driver of your peak demand calculation. Avoid starting the water softener at the same time as other large motor loads to prevent generator overload.
To determine the total generator size you need, use our interactive calculator to combine the water softener with your other appliances. The calculator automatically handles the starting surge calculation and applies the 25% safety margin to give you an accurate recommendation. Alternatively, browse the scenarios below to see common generator setups that include the water softener.
Tips for Running a Water Softener on a Generator
When running the water softener on a generator, the most important consideration is the starting surge. Before starting the water softener, check that no other large motor-driven appliances are starting simultaneously. Stagger your startups: let the water softener reach steady-state operation (usually within 1-2 seconds) before starting the next motor load.
If the generator struggles to start the water softener (indicated by the generator bogging down, lights dimming significantly, or the appliance failing to start), it likely means the generator's peak surge capacity is insufficient. Try reducing other loads before attempting to start the water softener again. If the problem persists, you may need a larger generator with more surge capacity.
Modern inverter generators handle motor starting surges particularly well due to their electronic power management. If you are purchasing a new generator specifically for loads that include the water softener, verify that the generator's peak (starting) wattage specification meets or exceeds the 100 W starting requirement plus the running wattage of all other connected appliances.
Water Softener Wattage Compared to Similar Appliances
The following table compares the water softener to other appliances in the water & plumbing category. Understanding relative power requirements helps you make informed decisions about which appliances to prioritize on your generator and where you might find opportunities to reduce your total load.
| Appliance | Running Watts | Starting Watts |
|---|---|---|
| Water Softener (this appliance) | 50 W | 100 W |
| Well Pump (1/2 HP) | 1,000 W | 2,100 W |
| Well Pump (1 HP) | 2,000 W | 4,200 W |
| Sump Pump (1/3 HP) | 800 W | 1,300 W |
| Sump Pump (1/2 HP) | 1,050 W | 2,150 W |
| Electric Water Heater | 4,500 W | — |
| Hot Water Recirculation Pump | 100 W | 200 W |
Frequently Asked Questions
How many watts does a water softener use?
A water softener uses approximately 50 watts of continuous (running) power during normal operation. It also requires 100 watts of starting (surge) power when the motor first turns on, which is 2.0 times the running wattage. This starting surge lasts only a fraction of a second but your generator must be capable of delivering it.
What size generator do I need to run a water softener?
To run a water softener by itself, you need a generator rated for at least 125 W (1 kW), which includes a 25% safety margin above the starting wattage of 100W. However, most people run additional appliances alongside the water softener, so your actual generator needs will be higher. Use our calculator to add your other appliances and get a comprehensive recommendation.
Can I run a water softener on an inverter generator?
Yes, a water softener can run on an inverter generator as long as the generator's peak (starting) wattage capacity meets or exceeds 100 watts. Inverter generators handle motor starting surges well and provide clean power that is safe for the electronic controls found in many modern water softener models. Verify the inverter generator's surge rating in the specifications.