A sump pump is the best way to keep your cellar or basement dry and protect your property from costly water damage, especially if your home sits below the water table or is prone to flooding. If you’re considering investing in a cellar sump pump, you must choose the right pump size. 

You’ll need to ensure you have enough capacity to deal with excess water in your basement. However, it’s important not to oversize your basement pump, as this can result in short cycling and reduce the lifespan of your pump. 

In this blog, we’ll cover everything you need to know about how to size a sump pump and how to choose the right pump size for your basement or cellar.

 

How to size a sump pump?

When calculating the necessary pump size for your cellar or basement, you’ll need to consider both the maximum vertical and horizontal distance that the device can pump. 

You’ll often see sump pumps rated by their ‘max head rate’. This term refers to the furthest distance the pump can pump water vertically. For example, a basement sump pump with a max head rate of 4 metres would not be able to lift water more than 4 metres upwards. 

However, it is not as simple as this, as you’ll also need to factor in the distance your pump will need to pump water horizontally. This measurement is referred to as the ‘total dynamic head or lift’. To calculate this, you’ll need to take the overall vertical lift, and for every 10 m horizontal stretch, add another 0.5m to the total lift. 

For example, a horizontal run of 20m plus a vertical lift of 2m equates to a total dynamic lift of 3m. When selecting the right pump size, you should ensure it has a head rate of 3 metres or slightly higher. Be aware that having narrow pipes could increase the friction and, therefore, the head rate you’ll require. 

It’s important not to oversize your choice of pump. It’s not recommended, for example, to purchase a pump with a max head rate of 10 metres when you require a minimum of 3 metres, as this will put too much back pressure on the pump, and it will burn out more quickly. This can significantly reduce the lifespan of your cellar sump pump. 

 

What size sump pump do I need for my basement or cellar?

When it comes to choosing the right size of sump pump for your cellar or basement, there are many factors you need to consider. Here are the main ones you’ll need to consider when deciding. 

Max head rate

The max head rate refers to the maximum vertical distance the pump can move water. You’ll need to determine the total dynamic lift required (using the calculation above) to ensure you choose the correct max head rate for your basement’s requirements. 

Flow rate

You’ll also need to consider the flow rate, usually expressed in litres per hour (l/h) or cubic metres per hour (m3/hr). This is the maximum volume of water the sump pump can pump away each hour through its discharge pipe. If your home sits below the water table or on sandy soil, you’ll need a higher pump capacity and flow rate. 

Sump pit chamber size

Another factor you’ll need to consider is the sump pit or chamber size. Smaller sump pump basins will fill up with water more quickly than larger ones, meaning the sump pump has to activate more frequently to empty it. This can shorten the lifespan of the pump and check valve. A pit with a larger diameter or depth will take longer to fill and should be considered, providing you have adequate space to house it. 

Single or twin pump

Most basement or cellar pumping stations are available with either single or twin pumps. Twin pumps can pump out higher volumes of water, and the second pump acts as a backup in case the first one fails. This ensures your basement stays protected even if one of the pumps fails.

Check out our blog, ‘Finding the best sump pump for your basement or cellar: what do you need and why?’, for a more in-depth breakdown of the factors to consider when choosing a sump pump. 

 

Basement and cellar pumping stations

At Sumps and Pumps, we stock a range of sump pumps to suit basements of all sizes and requirements. Our basement and cellar pumping system has a sump chamber and a single or dual submersible water pump. We recommend a twin pump system if you deal with higher volumes of water to protect your cellar from damage and give you peace of mind. 

We offer both budget-friendly pumping stations, which need assembling, and professional, ready-to-go cellar sump pump stations. Many of our cellar pumping stations feature a squat chamber to make the installation as simple as possible. 

We also offer high water level alarms, battery backups, pump control panels, and waterproofing products, so you can rely on our site for everything you need to waterproof your basement fully. 

Browse our full range of sump pumps, pumping stations and accessories in our online shop. If you need help selecting the sump pump size for your basement or cellar, please contact our team. We’ll be happy to offer advice and guidance.