Nitrates are naturally occurring compounds that are essential for plant growth, but when they are present in high levels in water, they can pose a serious threat to human health and the environment. There are several factors that have contributed to the increase in nitrate levels in UK water. One of the main causes is the excessive use of fertilisers in agriculture. These include both manufactured fertiliser and organic manure. When these fertilisers are applied to crops, the nitrates can seep into the soil and eventually make their way into water sources, such as rivers and lakes. In addition to fertilisers, sewage, and animal waste also contribute to the problem, as they can contain high levels of nitrates that can leach into the water supply.