Rainwater Harvesting: Pros and Cons

October 17th, 2012

Rainwater harvesting is becoming increasingly popular among US residents. If you are considering rainwater harvesting, read below to learn more about some of the pros and cons associated with having a collection system in your home.


Multiple Uses

Rainwater can be used to water indoor and outdoor plants, as well as lawns and gardens. Obviously, this is a more natural process than using water from a municipal water supply which means that it will likely be of a better quality and improve the health of your plants. It can also be used for drinking water and other household purposes as long as it is properly filtered and treated.

No Municipal Water Contaminants

Rainwater harvesting eliminates a lot of concern about many contaminants your water. The newly captured rainwater does not contain common municipal water contaminants like salts, minerals, disinfectants like chlorine, and additives like fluoride. Also, the pH of rainwater is almost neutral which most people find desirable.

Reduced Utility Bill

Many of us are all too familiar with the increased water bills in the summer months, especially if you live in a dry climate. By using harvested rainwater, you can reduce your municipal water usage and save money since rain is free! If you use rainwater for other household purposes like cleaning, washing, cooking, or even drinking, you will save a substantial amount of money throughout the year.

Alternative Water Source

When your usual water source is limited or not available, rainwater is a good alternative. If you live in a rural area with no other water supply than a well, consider harvesting rainwater to serve as a back-up if contamination or drought conditions occur. Residents of the state of Texas are subject to drought conditions and frequently promote rainwater harvesting in the news. Many rainwater harvesters enjoy the self-reliance that comes with having an emergency water supply.

Decreased Run-off

By diverting the flow of rainwater, you will reduce the amount of run-off on your property. This helps to reduce erosion, low level flooding, and flow to storm water drains. If your property is part of a combined sewer system, which collects rainwater runoff, domestic sewage, and industrial wastewater in the same pipe, heavy rainfall can cause overflows of untreated sewage into local water bodies. By harvesting rainwater, you are helping in a small way to prevent non-point source pollution.


Initial Expense

It is important to plan for an initial expense. The cost of the system will vary based upon the complexity. Simple systems frequently used to collect non-potable water (for gardens, etc.) primarily consist of a catchment surface, plumbing fittings, and something as simple as a garbage can to hold the water. If you are interested in connecting the water to your home, you may need to contact a professional. Furthermore, if you require larger storage, your largest expense by far will be the storage tank. Cisterns can vary in cost based on the material (polypropylene, fiberglass, wood, etc.) and by size. More expensive cisterns will cost several dollars per gallon. Other components you will need to purchase for a larger system include screens, filters, and pumps.

Operation and Maintenance

Unlike municipal water, you will have to take steps to operate and maintain your system. If you are using the rainwater for drinking water you will need to filter it. You will also need to maintain the pumps and clean the system regularly. It is recommended that you inspect the system twice a year to ensure that it is working properly.

Water Quality

While the rainwater lacks contaminants commonly found in municipal water systems, it has been found to contain trace amounts of air pollutants such as arsenic and mercury which are absorbed from the atmosphere. Since the rainwater is usually collected from your roof, the water can have feces, bacteria, dust, and other material that is small enough to pass through the initial screens. If you will be drinking this water, you will want to use a water purifier that can remove all biological and chemical contaminants.

Unpredictable Rainfall Amounts

Careful planning is necessary to avoid using more water than what you collected. You will need to be especially careful if you live in an area with dry spells because you will consume saved water rather quickly. Just remember that rainfall amounts are unpredictable so plan accordingly.


Some regulations may prohibit rainwater collection. For example, in Colorado the state claims the right to all moisture that falls within the state border. Consequently, a Colorado resident cannot divert rainwater to be used for a specific purpose unless there is a surplus of water in the river system, or if the individual has an older water right or is a domestic well-owner that meets specific conditions.

If, after reviewing the pros and cons, you decide that collecting rainwater is a good option and you would like more information, read our previous blog about rainwater harvesting.


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