Skip to Content

Is Rainwater Harvesting Worth It? Learn The Pros and Cons

Rainwater harvesting has been a centuries-old process for conserving water. But is it really worth it? Find out everything you need to know.

According to the UN’s Water Report in 2020, the world’s water consumption saw a six fold increase in the past century. According to the current estimates, consumption continues to grow by around 1% a year.

This simple stat is not as simple as it seems. Like all the other natural resources, water is also a scarce natural resource.

The scarcity of water is not a new phenomenon. The first official record of water scarcity goes back to the 1800s.

With the scarcity came practices to conserve water. Thus, rainwater harvesting became one of the many water conservation methods that the world adopted as a defense.

However, the question here is, is rainwater harvesting worth it?

But before answering this first question, let’s get detailed answers to all the possible queries related to rainwater harvesting. The takeaway? Thorough understanding of the process.

All You Need to Know About Rainwater Harvesting

We intend to answer the following questions in this section:

What is Rainwater Harvesting?

Rainwater harvesting is the collection, storage, and distribution of rainwater through a system. This method reduces the rainwater runoff, and instead of wasting rainwater people consume it in different ways.

How to Harvest Rainwater?

Typically, rainwater harvesting gets done through the rooftop of a building. For this reason, in some countries, the process is also known as rooftop water collection.

People direct the rainwater from their rooftops into a rainwater harvest tank. They do it through a waterspout such as Oatey downspout, through which the water goes into the harvest tank. After that, in the filtration unit and after that into a recharge well.

Mystic Rainwater Collection System

The above-explained process of rainwater harvesting is commonly used for residential purposes. For large-scale purposes such as watering the fields, this method may remain the same.

However, the scope of the process changes immensely, where large-capacity cisterns replace small water tanks.

What is a Rainwater Harvesting System?

A rainwater harvesting system is a collection of hardware to carry out rainwater collection, storage, and transportation.

More advanced rainwater harvesting systems use purification hardware and filters. After that, the treatment plants can make the rainwater fit for drinking.

What is a Basic Rainwater Harvesting System Design?

A basic rainwater harvesting design consists of the following components:

Catchments

The first part of a rainwater harvesting system is a catchment. A catchment is a surface from where the rainwater harvesting system receives water.

is rainwater harvesting worth it

The catchment can be any solid surface such as a rooftop, or a terrace. Not only a solid cemented surface, but people also use unpaved areas such as a lawn, as a catchment.

Cement and iron sheets are prevalently used construction materials for rooftops in developing countries.

Coarse Mesh

The coarse mesh is usually a fine metal net installed on a rooftop. It serves the purpose of restricting any debris from entering the gutters.

Gutters

Gutters are the structures installed at the edge of the inclined roof. They collect rainwater and dump it into the storage tank. You can make these by folding iron sheets or cutting a PVC pipe into half.

gutter

Experts use the highest intensity rainfall of a spell as the capacity measure of the gutters. However, if you don’t know much about the gutter size, you should consult an expert for the installation of a rainwater harvesting system.

Conduits

Conduits are the vessels that carry the rainwater from the gutters to the storage tank. These conduits can be made of either PVC or galvanized iron.

The capacity of these conduits should also depend on the most intense spell during a monsoon.

First Flushing

A first-flushing valve is a device that diverts the rainwater from the first rain of a season. The first flushing eliminates the chance of polluted water entering the rainwater harvesting system.

First Flushing

It is essential to flush the first rainwater because it has impurities from the environment.

Filters

The filter unit uses filter materials such as mesh, sand, and gravel. These filtration tanks have these materials at different levels to trap all the pollutants suspended in the rainwater.

Storage Tank

A basic rainwater harvesting system ends at a storage tank where water gets stored after the collection and cleaning.

See Related: Types of Waste Disposal: Methods and Approaches

What are the Different Types of Rainwater Harvesting Tanks?

There are three types of rainwater harvesting tanks:

Rain Barrels

Rain barrels are the standard tanks to install with a downspout gutter. These tanks directly collect water from the rooftop, and they have smaller capacities of 50-100 gallons of water only.

Rain Barrels

These rain barrels are either made of new or recycled material. However, there is a price difference in both the material types. These rain barrels are usually installed in residential buildings to collect rainwater to water plants only.

Dry Tanks

The second type of rainwater harvesting tank is known as ‘dry’ tanks that are huge as compared to the rain barrels. The whole process remains the same except for ‘drying’ of the collection pipe after every rain.

Wet Tanks

The third type of rainwater harvesting tank is known as a ‘wet’ harvesting tank, installed a little far from the building that needs to collect the rainwater. This type of tank uses underground water pipes that get filled with rainwater.

Wet Tanks

As the rainwater level increases, it fills the vertical pipes located at the sides of the tank with water. When the pipes start overflowing, they cause spillage inside the tank. These wet tanks are great to cover larger areas, hence, more water storage.

How to Install a Rainwater Harvesting System at Home?

Installation of a rainwater harvesting system is divided into the following stages:

Installation of the first flush diversion kit

The installation process starts with setting up the first flush diversion kit, such as clean rain advanced downspout diverter. The first flush is the rainwater from the rainfall of the first spell.

Fit the leaf eater

Once you get done with attaching the downspout diverter’s parts, fit the leaf eater on top of the kit.

Mount the filter system

You have assembled the first flush diversion kit now. At this stage, mount the whole diverter on the wall, attaching it with the roof’s downspout.

Attach the joiner pipe with the tank

Reservoir

Connect a joiner pipe that goes into the tank. You can choose a tank such as Robotech horizontal with legs for extra storage capacity.

Install a pump with a tank connecter kit

Now you are in the last stage of the process. You have to install a pump to water your garden. Attach a pump such as the Waterace Transfer Pump, and attach it to your garden hose to water all your plants.

What are the Different Ways of Rainwater Harvesting?

Surface Runoff Harvesting

Using surface runoff harvesting, rainwater is collected naturally in the water bodies, storage tanks, or aquifers before the water gets evaporated.

Rooftop Rainwater Harvesting

Rooftop harvesting uses rainwater from paved surfaces directed either towards a storage tank or a recharge-pit (an underground well) that slowly seeps the water into a particular area’s underground water reservoir.

Dams

Dams are massive water storage infrastructure that stores water through direct rainfall. They create a barrier for water to seep into the ground.

The water stored in dams is then treated and pumped to the localities for residential and commercial usage.

file 20190912 190031 rvcefl

Underground Tanks

The underground tanks are usually cemented from the inside to reduce seepage. They are closed from the upper part as well and use pipes to store rainwater in them.

The underground tanks conserve rainwater better. The reason is a low chance of evaporation of water due to the lack of direct contact with sunlight. Water stored in underground tanks is also safe from the growth of algae.

Rain Saucer

A rain saucer is a funnel-shaped structure that has a pipe attachment at the lower end. The waterfalls directly into the broad upper part from where the pipe takes it to another storage vessel such as a tank.

Water Collection Reservoirs

By this method of rainwater harvesting, people collect water from the roads and passages. The water thus collected is not clean, but you can use it for irrigation of the agricultural lands.

Barrage

A barrage is a dam constructed over rivers that have openings to control the water flow. Barrages open and close with the water flow increasing and decreasing, and they have huge water storage capacity.

Barrage

Slopes

The naturally occurring slopes and those made by men can collect water at their ends.

Trenches

Trenches are depressions in the land to collect rainwater. After the collection of rainwater, these trenches divert the water towards agricultural land to irrigate them.

Rain Barrels

Rain barrels are small water storage tanks that can be used for rainwater harvesting. They can be made of materials such as PVC.

Is Rainwater Harvesting Worth It? FAQs

Here are some common questions about rainwater harvesting.

Who Can Harvest Rainwater?

Anyone can harvest rainwater. People do it on a small scale for residential uses, such as for watering their plants. There are industrial uses of the rainwater as well, with huge rainwater harvesting systems.

Should I Implement Rainwater Harvesting?

If you are residing in an area where you experience water shortages throughout the year, you should implement a rainwater harvesting system, at least on the residential level. The system can give you the ease of using stored water for various tasks around the house.

How Much Rainwater Can I Collect?

Rain drops

You can easily calculate the quantity of harvested water by multiplying the catchment area (sqft or sqm) with the amount of downpour(mm) in a particular spell. It would help if you reduced a small percentage of water to compensate for the lost water during the process.

Is it Illegal to Harvest Rainwater?

It is not entirely illegal to harvest rainwater. However, in some states of the US, there are restrictions regarding the usage of harvested rainwater.

In many states, rainwater harvesting is highly regularized by the laws that cover the storage tank’s capacity, the use of harvested rainwater, and many other factors.

Can We Use the Harvested Rainwater for Cooking and Drinking Purposes?

As the rainwater falls on the ground, it catches impurities present on the surface. The residentially harvested rainwater is not fit for cooking and drinking purpose even after the filtration process.

The filtration process only cleans the physical impurities and does not change the chemical contaminants of the rainwater. Therefore, People can use harvested rainwater in watering the plants and for cleaning purposes, but not for cooking and drinking.

What are the Commercial Uses of Harvested Rainwater?

Besides the residential purposes of harvested rainwater, the commercial uses of rainwater include:

  1. Irrigation
  2. Fire-extinguishing
  3. Manufacturing processes that require water
  4. Commercial washing of vehicles
  5. Filling up pools
  6. Commercial laundries

Pros and Cons of Rainwater Harvesting

Now that we have answered many of the questions about rainwater harvesting, it’s time to see the process’s benefits and downsides.

Pros of Rainwater Harvesting

Environmental benefits

  • Reduction in Storm Runoff: Rainwater harvesting can reduce the quantity that dumps into the water bodies with every spell of rain.
  • Less Contamination of Water: This reduction in the runoff can protect the water bodies against contamination with chemicals and metals that flow with the rainwater.
  • Storm mitigation: Rainwater harvesting can be very beneficial against storms in the nearby rivers and other water bodies.

Economic Benefits

  • Availability of Water for Irrigation and Commercial Purposes: You can use the harvested water in the irrigation of local gardens and other commercial purposes such as laundry and commercial cleaning.
  • Low Water Treatment Cost: Rainwater harvesting reduces the energy cost involved in pumping and treating water by the municipalities for the residential buildings.
  • Lower Water Bills: Rainwater harvesting is an excellent alternative to municipal water, and it reduces your water bills.
  • Affordable Infrastructure: If people start adopting residential rainwater harvesting as a DIY method, the overall infrastructure cost for water management will go down.
  • Provision of Jobs: The rainwater harvesting process, if implemented on the state level, can produce jobs.

Benefits as an Alternate Water Source

  • For Agricultural Land: Harvested rainwater can be used in agricultural irrigation. If you have a greenhouse garden or a traditional garden, you can use the water to water your plants instead of using water from your utility.
  • Areas with Low Water Reserves: Rainwater harvesting can benefit those areas immensely where there is no other water source, or it is hard to get water even if available.
  • As an Alternative for Hard Water: For residential purposes, people can easily use rainwater for laundry and dishwashing compared to hard water that leaves residual marks on both.

Cons of Rainwater Harvesting

  • High Initial Cost: The cost of setting up a rainwater harvesting system can be huge. For residential structures, it may be low, but the commercial systems are quite expensive to install.
  • Maintenance: Maintenance of a rainwater harvesting system is a tedious task. The tanks, filters, and all other fittings require regular cleaning to avoid the invasion of algae, small animals, and different kinds of debris build-up.
  • Unpredictable Rains: You cannot predict rainfall, so there is no assurance of maximum capacity. Similarly, harvested water can finish before the next spell of rain.
  • Chemical Seeping and Other Pollutants: In the case of a rooftop rainwater harvesting system, there may be the problem of chemical seepage from the roof’s materials. Other pollutants such as bird droppings and debris from the air can also get to the stored water.
  • Storage Limits: Storage limits can be tricky to handle. There may be a heavy rain spell and you o not have enough capacity to store water, or there may be a light downpour that doesn’t fill up the storage tank enough.
  • Water Treatment: Just like the municipal water harvested, rainwater also requires treatments before it becomes completely fit for drinking. It may incur extra costs other than the setup and maintenance costs.

Is Rainwater Harvesting Worth It: Final Words

So is rainwater harvesting worth it? There may be some cons to the rainwater harvesting process, but the potential benefits are way more than those disadvantages.

With the world moving towards depleting water resources, it is high time to look for better conservation methods and better consumption options.

After answering many of the possible questions about rainwater harvesting and gauging its pros and cons, we are at a safe point to say that rainwater harvesting is worth it. It should become a primary water conservation method.

Related Resources