The concept of retrofit rain harvesting is not new, but its adaptation in urban areas is gaining momentum. This environmentally-friendly solution for water scarcity offers a sustainable way of reducing our water footprint by collecting and reusing rainwater. However, while retrofit rain harvesting has significant environmental benefits, it also presents several costs and challenges that need to be considered. This article aims to evaluate the financial implications and obstacles associated with retrofit rain harvesting.

Assessing the Financial Implications of Retrofit Rain Harvesting

Retrofit rain harvesting has an upfront cost which is often the most significant financial obstacle. The cost includes the price of the equipment such as the water tank, gutters, filters, pumps, and other installation materials. Additionally, there is the labor cost for the installation of the system. The total expense can range from a few thousand pounds to the sky, depending on the size and complexity of the system.

However, it’s crucial to evaluate these costs in the context of long-term benefits. A well-designed retrofit rain harvesting system can lead to substantial savings on water bills. By using harvested rainwater for non-potable needs such as irrigation and washing cars, the reliance on municipal water can be reduced, thus lowering the water bills.
Using rain water for watering garden plants is the most natural way and the best water source for them.

Moreover, some regions offer financial incentives in the form of rebates or subsidies for installing rainwater harvesting systems, which can offset the initial installation costs. It’s important to inquire about such programs in your local area. Additionally, since rainwater harvesting contributes to sustainability, the property value might increase, making it a sound long-term investment.

The cost of maintaining a rainwater harvesting system is another factor to examine. Regular inspection and maintenance are necessary to ensure the system works efficiently. This includes cleaning of gutters, filters, and the tank, which could mean additional costs if professional services are employed.

Key Aspect: The Scaling

Unless we are forced to store as much rain as possible, then the designing starts here. At retrofitting rain harvesting it used to come from the other direction: the first thing to know is the amount of water that will be used regularly. We used to advice storing 3-4 liters water for every squaremater of the garden surface, where the irrigation is necessary.

It means that 3 m3 of water is sprayed over on 1000 sqm a day or 100 sqm on 20 days (watering every 2nd day only). This is acceptable amount of water in the UK summer days.
We only can guess from this point, as the weather is as sure as the weather 🙂 But let’s say that a long 30-day drought period is usual twice in a year but there are rainy days between them so take that 30-day into consideration.

When the space is not an issue, then 4.5 m3 capacity is acceptable for every 100 sqm. For knowing your size, just grab your tape measure and take the numbers from your garden!

See The Numbers: Does It Worth Compared To Mains Water?

You can easily get answers for costing a tank via a web search but can’t get it for installing the tank. But there are lots to consider inlcuding approaching the area with machines, storing the soil, moving the tank and concrete, etc. Better to get in touch with a builder and request a quote for the whole process.

But for our example, let’s say that the cost for installing a 10m3 tank is 10 thousand pounds in 2024. Taking the shortcut: it means every liter of rain water saved need 1 £/l initial investment. And this is the time when you should have a look on your water bill: how much is a m3 (1000 l) mains water? It is influenced by some other circumstances but somewhere below 2£/m3. That’s 0.002£/liter! From other point of view, you will invest your money for an invisible 0.002% interest.

We don’t want to talk you out of having rain harvesting, as it’s good for the plants, can reduce your usage bills and key for the environment. We just wanted to call your attention to the numbers.

Of course, a rain harvesting tank may improve the property value and then the final balance may be positive. And it’s also possible that you must install rain harvesting equipment due to local regulations. But strictly looking at the retrofit rain harvesting: it is not a profitable investment.

Navigating the Hurdles in Retrofit Rain Harvesting Implementation

While retrofit rain harvesting can be a highly resourceful practice, it doesn’t come without its challenges. For instance, the lack of space for installation could be a significant issue in densely populated urban areas. The system requires enough space for the storage tank and the piping network, which might not be possible in some properties.

It’s a very popular solution to use underground storage tanks if there are unused spaces, like under the terrace. Unfortunately retrofitting a tank under existing surfaces may lead to some unsolvable problems. Including but not limited to moving existing services, breaking up the paving, taking away the soil, etc.

Another problem relates to legislation and regulations. In some jurisdictions, there might be restrictions that limit the use of rainwater or the installation of harvesting systems. It is therefore crucial to familiarize oneself with local laws and regulations before beginning the setup process.

Also, collecting and storing rainwater can sometimes lead to water quality issues, especially if proper maintenance is not carried out. Bacteria, algae, and other pollutants can contaminate the water, affecting its usability. It is imperative to ensure that the harvested rainwater is treated and filtered appropriately for its intended use.

Lastly, the varying and unpredictable nature of rainfall can pose a challenge. Rainwater harvesting is highly dependent on rainfall patterns. In areas with lower rainfall, the benefits of the system may not be fully realized. Therefore, it is important to consider local climate and weather patterns when planning a rainwater harvesting system.

In conclusion, while retrofit rain harvesting presents a strategic solution to water scarcity and sustainability, it also involves significant costs and challenges. The financial implications, regulations, space constraints, and weather patterns are all critical factors to consider when evaluating the feasibility of retrofitting a rain harvesting system. Nonetheless, with careful planning and consideration, the benefits of rainwater harvesting can significantly outweigh the challenges, making it a worthwhile investment for a sustainable future.