25 July 2024

What is the best colour for a water tank?

Many people in New Zealand are choosing to install a water tank at home. There are many great reasons for installing a water tank including environmental and financial. You can read more about the benefits of rainwater harvesting in a recent post.

If you are considering whether to install a water tank, one of the questions you will inevitably face is what colour of tank you should opt for. Whilst there are a few options when it comes to the type of tank you install, including concrete and stainless steel, by far the most popular water tanks for home installation are polyethylene water tanks (poly tanks).

They are often known as plastic water tanks, and they are extremely versatile both in terms of the shapes they can be moulded into and the ease of installation because they are lightweight.

Polyethylene is the perfect material for constructing water tanks. It is non-corrosive and will not rust during its service life. They are typically made from a single piece of polyethylene with no joints or seams. This makes them less likely to leak than a concrete tank.

Poly tanks can also be recycled at the end of their service life, making them a more sustainable and even greener option than concrete tanks.

Another versatile aspect of poly tanks is the fact that they can be manufactured in a range of colours.

Does the colour of my water tanks matter?

There are a few conflicting schools of thought when it comes to the best colour for poly water tanks. Some say that darker water tanks are better because they help to prevent the growth of algae. Algae thrive in sunlight so the more light that the water in your tank is exposed to, the more chance you have of developing algae.

This, however, doesn’t mean that lighter-coloured water tanks are a breeding ground for algae. Most light-coloured water tanks are opaque and manufactured with an adequately thick wall to prevent algae from forming.

Other sources suggest that darker tanks actually provide a better breeding ground for algae and bacteria. This is because they absorb more heat from the sun that lighter coloured tanks and warm water is conducive to bacteria and algae growth.

The truth of the matter lies somewhere in between. Today, all water tanks, no matter the colour, are manufactured to a high standard and are designed to minimise bacteria and algae growth. Most people today, instead pick the colour of their water tank for aesthetic reasons, to match the environment in which it will be installed.

Choosing a water tank on looks

Today, most people select the colour of their water tank to match the environment in which it will be installed. Whether this is next to the house, along a fence line or in the garden.

The only downside with this is that people often refresh their houses, or their fence more often than they need to change their water tank.

That’s why it makes sense to choose a relatively neutral colour. A neutral colour of tank, such as beige or a lighter green will be more versatile moving forward and give you greater flexibility with future changes.

Sometimes, people will also purchase a water tank in a specific colour because it is a cheaper model. If you don’t love the colour, there is plenty you can do to screen your water tank. From man-made screening to natural screening to utilising your fence line, there are many ways you can screen your tank so no matter what colour it is, it will always blend into its surroundings.

Practical colour considerations for your water tank

Whilst the aesthetics of your water tank are undoubtedly important, there are some practical considerations as well.

We have discussed the differing opinions regarding the colour of your water tank and the likely breeding ground you create for bacteria and algae. This is definitely something to consider and something you should talk to your water tank supplier about.

The colour also affects the temperature of the water you are storing as well. This is especially important if you plan to use the water you collect for potable purposes (drinking, cooking, bathing etc).

A dark-coloured water tank will absorb a lot more heat from the sun than a lighter-coloured tank and during the warm summer months, this means the water in your tank is likely to be much warmer than a lighter-coloured tank.

Whilst we have discussed the potential impact on algae and bacteria of having warmer water, it is also not that refreshing to drink warm water so this is a consideration you should factor in. If you are only collecting the water for watering the garden or washing the car, this will be less of a consideration.

There has been some research conducted to suggest that lighter-coloured tanks also have a longer lifespan than darker tanks. Whilst all poly water tanks are built with UV protection, the research suggested that some colours lasted longer than others. Lighter-coloured tanks like beige or light green, for example, were found to outlast their darker compatriots such as dark green, black or blue.

This should be a consideration, especially if you plan to locate your tank in direct sunlight. If possible, we always recommend positioning your tank in a shady position or using screening to protect your tank and help to keep the water cooler.


There are both practical and aesthetic considerations to factor in when you are purchasing a water tank.

When it comes to measuring the amount of water in your tank, the colour doesn’t really matter. One of the biggest barriers for people adding a rainwater tank at home is the uncertainty of not knowing how much water is left in your tank. This applies to rainwater tanks stored both above and below ground.

At Smart Water, we have engineered the most advanced tank level indicator available that now offers full cloud connectivity. 

Easy to install yourself, your Smart Water tank indicator provides you with all the information you need from our app or from one of our LCD displays. Find out how much water you consume on average from your tank, accurate pressure data and estimates on when your tank will run out of water based on current usage.

Find out more about our range of products or check out our FAQs for more information.