The Hosepipe Ban – Should watering vegetables be excluded?

So once again, there is a hosepipe ban imposed across eastern and south-eastern England and Grantham is included.

The reasons for the ban are clear – if everybody takes care over their water usage now, the supplies we have will last longer, the rate at which we deplete them will decrease and the chances of more serious problems down the line will be reduced. It will also reduce pressure upon our reservoirs and waterways which will have clear ecological benefits. In summary, I am in favour of the ban.

However, it does appear short-sighted of the water companies to not exclude watering vegetables from this ban. It shows just how far we have become separated from our food and any form of self-sustainability that watering vegetables is considered a non-essential use of water, along with washing the car and hosing down the patio. Growing your own food should not be considered a luxury we can do without.

Technically, we can water with a watering can and therefore keep our own crops alive, but I know of many people who are not growing their own this year because the time and effort required to keep them alive without the use of a hosepipe are too great. This means, that more people will be buying their vegetables from the supermarket.

There was a study produced by the WWF in 2008 which looked at the water footprint of different countries and different crops. In the same year, a paper was published at waterfootprint.org which provides a table of average water footprints for a range of different produce. This takes into account, not only the quantities of water required for the industrial scale watering and growing of these crops but the water uses involved in processing, transportation and retail as well as accounting for pollution caused by nitrogen fertilisers and other harm to water supplies.

Taking a simple example, the average water footprint of 1kg of tomatoes is quoted as 180 litres of water.

Now logic dictates that removing all of the supply chain, haulage, processing, retail (including spraying vegetables with water to keep them fresh and other such activities) should reduce the water footprint of a home-grown tomato drastically. Even in terms of simple watering, your garden soils will hold a lot more water than arable fields where the soil structure is damaged from years of intensive agriculture.

So how much water would it use to grow tomatoes at home? A quick back of the envelope calculation from a few sources on the internet:

The average tomato plant produces around 2.5kg of tomatoes.

The water requirement of a tomato plant varies between 0.14 – 1.8 litres per day, depending upon the weather conditions. I am taking the figure of 1 litre per day as the average for ‘fairly sunny’ – ‘sunny’ weather as this will probably work out approximately correct across the average English summer. This is for the grown plant as well so it would be a conservative average as I am including the pre-flowering and pre-fruiting stages in the next step.

The average growing season, from the point at which the seedlings have developed to the point at which they are ready for harvest, is around 3 months, 90 days.

In theory therefore, a home grown tomato should be able to produce 2.5kg of fruit for 90l of water. If we scale the water footprint of commercially grown tomatoes up to the 2.5kg level, this is a huge 450l of water. A home grown crop of tomatoes should produce the same yield using one fifth, 20%, of the water required for a commercial crop of the same weight.

Whilst I accept that a few things may be missing from this calculation; you will probably wash your tomatoes when you bring them in, you may use a small amount of fertiliser etc., this is unlikely to make a big impact on the huge scale of the difference between these two figures.

Overall therefore, people should be encouraged to continue growing their own produce if we want to save on water use and deterring people from doing this seems short-sighted on the part of the water companies. I have framed this argument entirely in terms of water but there are of course multitude other advantages to growing your own – it cuts down on fertiliser, pesticides and carbon emissions as well as other greenhouse gasses and, of course, it tastes better.

Therefore, whilst I do support the hosepipe ban, I feel there is a strong argument that vegetables and other home produce should be excluded from this.