14 June 2024

Is rainwater clean for laundry?

We’ve all been there. You look at the weather forecast in the morning and there is not a raindrop in sight – a perfect day for drying your washing outside but sure enough, as soon as you leave the house and you’re out of sight, the heavens open and the rain begins to fall.

The big question when you get home is what to do next. Do you rewash the entire load or do you just wait for it to dry and treat it as normal? Will the rainwater have made your clothes dirty or smelly or is it just like another rinse cycle?

The truth is, there is no right or wrong answer to this age-old question. In the end, it comes down to personal preference as well as some other factors that might impact the cleanliness of your washing after it gets soaked by rain including:

·        How long it was hanging in the rain

·        The wind direction

·        Any road works or building work going on near your property

·        Where you live

Rainwater in itself is considered to be clean for washing clothes. Rainwater is naturally acidic, and this means it is naturally soft. Depending on where you live, your mains water could be a much harder water that needs to be treated to decrease the hardness. Soft water does not contain dissolved materials and minerals such as calcium, magnesium, iron, and manganese so theoretically, when it rains, that water is clean enough that there should be no negative impact.

The problem is that on its way to the ground, it can pick up pollutants and contaminants in the air.

Dust is another issue, although this can be an issue regardless of whether it rains when your washing is put out or whether you put your damp washing on the line. If there is a lot of dust in the area and your clothes are still wet, then there is the potential that these dust particles could land on your washing and make it ‘dirty’.

This can be particularly prevalent if you live near a new housing development, unsealed roads, mines and quarries, agriculture, or forestry activities. Sometimes the wind direction can play a big part in whether your clothes attract these particles or not so there is no definitive answer to this question.

Why do my clothes smell if they get rained on?

Often people that are in the ‘rewash the load’ camp will complain that their washing smells after it has been left out in the rain, however, the truth is that any washing that is left damp for too long will start to smell.

This is because a damp and warm environment encourages the growth of bacteria and mould and this is what generates the musty smell on your clothing. It’s no different to forgetting you put a load of washing on and then letting it sit damp in the machine for hours or even days. That washing always comes out smelling musty, even after a couple of hours and often needs rewashing.

Again, if there is a short rain shower and then your washing dries straight away, it is highly unlikely it will smell any different to how it would without the rain. If you choose to leave it out on the line for a couple of days through a series of rain showers, it is likely to develop a musty smell that will mean it needs rewashing.

What about rainwater harvesting for washing clothes?

Here in New Zealand, rainwater harvesting is becoming increasingly popular, especially for people that want to use it for activities like flushing the toilet, washing clothes, and watering the garden in the summer.

Whilst rainwater can collect pollutants as it falls to the ground, as well as pick up pollutants from the roof before it is collected in a rainwater tank, most rainwater tanks, even those that are not used for potable purposes (drinking, cooking etc), are fitted with a filtering system so the water that comes out is not the same as the water you collect. Microfilters collect even the smallest particles of dust and debris, meaning the water you collect from your roof is perfectly safe for washing clothes in your washing machine.

As we have already touched upon, the acidic nature of rainwater means that is it also a soft water which is better for washing clothes than a harder water and less hard-wearing on your washing machine and parts.

Collecting rainwater in New Zealand

Rainwater is a great way to supplement your mains water supply here in New Zealand, or for many properties, it is the main source of water to a property.

Washing your clothes with rainwater is a great way to conserve water and cut down on your monthly bills. Whilst you will need to make adjustments to your water supply in order to hook up a rainwater tank to your washing machine and also for flushing your toilets, the short-term costs will pay for themselves over time as you no longer need to pay for the water you use to wash your clothes or flush the toilet.

If you have a young family, the washing machine can run every single day and collecting rainwater from your roof is a great way to keep costs down.

You can read more about the basics of collecting rainwater here in New Zealand in our beginner’s guide to collecting and using rainwater. Here you will find handy tips on selecting the best rainwater tank for your needs as well as the process of filtering and connecting your rainwater tank to your property. You can also find out more information about Smart Water’s range of rainwater tank indicators – helping you to keep on top of your water usage and ensure you are maximising the rainwater you collect.