Last Updated: Tuesday, 13th February 2024

Demystifying Accumulator Tanks: What They Are and Why You Need One

If you've ever wondered, "What is an accumulator tank?", you're in the right place. This article aims to demystify the subject, covering everything from its purpose to installation. Whether you're a homeowner or a professional, understanding the ins and outs of accumulator tanks can save you both time and money.

What Does an Accumulator Tank Do?

An accumulator tank is a tank vessel that stores water under pressure. When used in the home, it's purpose is to improve the efficiency of your water system by taking mains water and storing under pressure to maintain a constant water pressure and flow rate inside your entire home.

How Does an Accumulator Tank Work?

Diagram showing how an accumulator tank works

The accumulator tank works by using two chambers separated by a diaphragm or rubber membrane. One chamber is filled with water, while the other is pressurised with air. When you open a tap, the pressurised air pushes the water out, ensuring a smooth and consistent flow. After use, the tank refills itself during periods of low demand, preparing for the next cycle.

If you use more water than the accumulator tank can store, then your water pressure will revert to whatever the mains water can supply.

When Would I Need An Accumulator Tank?

Accumulator tanks are great for those who have any combination of the following issues:

  • Poor mains water pressure: If you've noticed that your water pressure fluctuates, especially when multiple outlets are in use at once, an accumulator tank can help maintain a consistent flow across your home.

  • Frequent shower pump usage:If have a shower pump that is consistently in use, turning on and off frequently during the day, this can not only annoying but also puts strain on the pump. An accumulator tank is designed to provide constant pressure and can help reduce this type of cycling, prolonging the lifespan of your system.

  • Noisy shower pumps: Water systems can sometimes be noisy, especially when a shower pump kicks in. An accumulator tank can help dampen this noise, leading to a quieter home environment.

  • High water demand:In settings where water demand is high - think multiple, advanced showers running simultaneously in a home or other industrial applications - an accumulator tank is usually chosen to ensure that the system can meet this demand without faltering.

  • Energy efficiency:If you're looking to make your home more energy-efficient, an accumulator tank can help. By reducing the demand on shower pumps, you'll be saving energy, repairs and, by extension, money.

Where Does an Accumulator Tank Go In My Home?

When installed in your home, the accumulator tank will sit after the stop-cock, but before every other appliance and outlet in your home. Consider the diagram below:

Diagram showing where an accumulator tank goes in your water system in the home

Accumulator tanks can be used in combination with both combination boilers and system boilers with unvented cylinders. Naturally, they then also support every other appliance and outlet in your home.

What Size Accumulator Tank Do I Need?

Accumulator tanks come in a variety of sizes; typically this looks like a capacity of 60 litres all the way up to 450 litres. For those requiring even more volume, multiple tanks can be connected in series, ensuring you can find a solution to meet your specific needs.

Choosing the right size for your accumulator tank is crucial for optimal performance. The size you'll need generally depends on the size of your home, how many outlets you need to serve at any one time and the demand of each outlet. Larger systems will naturally require bigger tanks. If you're unsure about the size, it's better to go for a larger model to ensure trouble-free operation.

Cost Considerations

Generally, the larger the tank, the steeper the price tag. Prices can range from around £500 for smaller models to upwards of £1,500 for larger ones. It's worth noting that these figures don't include additional expenses like installation, fixtures and pipework, which will push the total cost even higher. Additionally, you may also need to invest in a pump, adding to the overall expenditure.

Advantages/Disadvantage of Accumulator Tanks


  1. Accumulator tanks do not need electricity to work, reducing your energy usage,

  2. They can deliver higher water volumes than the mains water can supply,

  3. They deliver consistent and reliable water pressure throughout your entire home,

  4. They operate quietly,

  5. They require relatively low maintenance.


  1. Cost.

Wrapping Up

In summary, accumulator tanks serve as an adaptable and effective solution for a variety of water supply challenges. Whether you're grappling with inconsistent water pressure, frequent pump cycling, or higher water demand than the mains inlet can supply, an accumulator tank could very well be the answer to your woes. Not only do these tanks offer the benefit of a more stable and reliable water supply, but they also contribute to energy efficiency and reduced wear and tear on your water system.

While the upfront costs can be a bit steep, especially for larger models, achieving the flow rates they deliver are largely otherwise unachievable. However, it's crucial to consider factors like size, placement, and local regulations to make the most out of your investment.

So, if you're in the market for a more efficient and reliable water system, an accumulator tank should definitely be on your radar. It's not just a purchase; it's an investment in a smoother, more efficient, and more comfortable lifestyle.

Any more questions?

If you have any queries or questions about the products we sell, or even your next project, give us a shout! We'll try our best to give you a hand.