Can you place your water tank in direct sun?May 19, 2018
Water tanks can be situated above ground or underground, depending on a variety of factors. Underground tanks can save space if you have a small yard, and they can allow you to install a larger tank than you could ordinarily accommodate on the surface. This is a combination of space and weight limitations.
If your tank is underground, you probably don’t have to worry about sunlight, because most of the tank is beneath the ground surface. The main problem with direct sunlight is that the accumulation of heat and ultraviolet rays encourages algae to grow inside your tank, making it unsuitable for human use.
In a swimming pool, chlorine, algaecides, and other chemicals are used to manage organic contamination, but it’s not advisable for tank water because getting the balance right can be tricky. In some parts of the world, chlorine is added to municipal tap water, but the water in rainwater tanks is generally stagnant, so any chemicals you add to it at home won’t circulate and can soon reach toxic levels.
However, sometimes it’s necessary to position your tank in the sun, so you have to use other means of preventing algae growth. Fortunately, you do have options beyond chemicals. You could build a shade or canopy above your tank, and that will minimise the amount of direct sunlight getting to your tank.
It doesn’t have to be a fancy shade. You could simply install a strong roof made of metal or plastic. Metal is a good heat conductor, so be sure to select a UV-resistant material like Colorbond or Zincalume. Both are treated with reflective paint that is baked onto the metal sheet. Check that the roofing overlaps the tank on all sides so that light doesn’t reach the tank from the sides.
The material used to make the tank itself can also act as an inhibitor to algae. Choose something with smooth sides so that the algae have nothing to latch onto. Corrugated tanks are popular, because they are more stable than flat or curved tanks, but the corrugated surface gives algae a better grip, so you’d have to weigh the pros and cons of that.
Paint in black
You might have noticed that while tanks are available in a wide array of colours, most people prefer them in black or glossy silver. This is because these are the best colours for preventing sunlight from getting into the tank. Food-grade polyethylene is a good algae deterrent, and so is concrete, so if you live in a sunny tropical region, these are your top materials for rainwater tanks.
Of course the best way to keep algae under control is to take good care of your tank. On average, it’s advisable to have your tank professionally drained and cleaned every two years, just before the rainy season, but if you live in an area with a lot of sunshine – like most of Australia – then you can up the frequency to two or three times a year.
The presence of algae and other micro-organisms make it unsafe for you to get inside your tank, so put aside some money to hire a professional tank maintenance crew that is trained to deal with this. The cleaning process is fairly straightforward, but you’ll still need some help with it, to avoid adversely affecting your health.
Basic tank maintenance tips
Generally, the tank needs to be emptied, then a long-handled brush will be used to scrub the sides and bottom of the tank, dislodging any algae and other germs and allergens that may have stuck to the sides. If there’s a layer of residue at the bottom of the tank, that can be scrubbed off too. The whole cleaning process can be done by hand or you can use a high suction vacuum to do it.
Any detergent used in the tank should be food-grade, so mild dishwashing liquid is best, and it should be agitated to a high foam, making it easier to rinse off. After getting rid of all the surface dirt and draining it, use a high pressure hose to get rid of all the soap and any dirt that may be left over. Ensure that every last soap bubble is washed away, then dry the tank completely before filling it up again.
As part of your tank maintenance routine, clean all the gutters, downpipes, and inlet pipes, because sometimes, the algae accumulate in these hollows before finding its way into the tank. You should also install a good mesh filter at the top of the tank, to prevent bio-contaminants and sunlight from sneaking into the water tank.
So, to answer the question – can you position your tank in direct sunlight? Yes, you can, but it’s not the best idea, so if it can’t be avoided, pursue the measures we’ve discussed to keep potential algae infestations under control.