Grey Water Harvesting
Grey water harvesting

With the high rate of desertification that is brought about by industrialization, and Global Warming water resource are becoming more scarce. It is due to this reason that governments and other stakeholders are working on innovative ways of preserving water resources. Grey Water Harvesting has become a reality for Capetonians as we struggle to avoid DAY ZERO. Never in known history has the drought-ravaged Western Cape been this close to day zero.

Recycling of water has been developed in many aspects, one of them being the production of grey water. This innovation, which is a natural partner, has come at a time it is in most dire need. Grey water is one of the means that the government of South Africa recommends to create massive water savings among homes.

Upon realization that up to 50% of the households’ potable water is diverted to the field, the South African government and stakeholders have diverted their full attention to the subject. In Cape Town, water is an issue with the growing population and limited water resources.

Therefore, one of the most effective ways of water management is the adoption of grey water. Grey water harvesting is the better option that saves the planet’s most valuable resource, water.

In fact, Cape Town is one of the places that have been stricken with severe water restrictions among the households. The pinch of higher water tariffs is being felt from all angles. Everyone is now conscious of every drop of water that lands on the cistern. Climate change worldwide as a result of global warming has made massive changes in weather patterns effecting rain and heat.

Brief History of Grey Water Harvesting

Recurrent poor management of waste became a global issue when diseases started breaking out. Every corner of the world was characterized by this unsanitary practice. The first water management control system was the sewage treatment.

Although it is not precise in history concerning the first ever sewage plant, It is estimated that sewer was in Paris. The initial purpose was to manage waste, which is held up-to-date. The driving factor, however, was the means to curb the alarming rate of disease outbreak by then.

The historical focus of waste management was anchored on diverting the effluent to a large water body mass. The process, therefore, depended highly on dilution and dissipation for treatment.

Over the years, there has been a dramatic change drifted to the current situation by technology. Concerns about water pollution have been raised. Thus, every waste has been addressed with a management solution with one of the most current one being the one being Grey Water management.

What is Grey Water?

Grey Water Harvesting is any domestic water that is viewed as waste in one aspect while it is most useful. It is water that is used for home purposes like showers, washing machines, and tubs. It does not include the sewage. Sewage is generally termed as black water and has an organic residue at a higher capacity. Sewage water has come into contact with dirt from the toilet.

Kitchen water can as well be categorized as black water as it contains some organic loading. A majority of people have woken up to the advantages that Grey Water Harvesting brings along.

Grey Water may harbor some traces of food, Grease, hair, or even some household cleaning products. Although it may be viewed as dirty water, it is safe when seen from an irrigation angle.

When Grey Water is left to stream into the rivers, lakes or estuaries as effluent, it becomes a pollutant. The constituents in the water can make the water becoming hazardous. On the other hand, these constituents when diverted to the plants, they become useful organic fertilizer.

The easiest means to use grey water involves piping it directly outside and use it to water the intended plants and fruit trees. Grey water can as well be used to water vegetables.

A grey water system requires one to use “plant friendly” products devoid of excessive salts and chemicals like boron and chlorine. This is because the buildup of these chemicals (salts and boron) in the soil may harm plants.

The presence of fat content in the kitchen water is a further damaging factor to plants.

What is Grey Water Harvesting?

It is the tapping of the already used water for it to put into a more useful form. Unlike the harvested water from other sources like the rainwater, grey water is obtained from sources that have already used the water.

These sources might include the water from the sinks, bath water, ponds, pool backwash or even the rinse water. In some cases, it is harvested to be used for toilet flushing. When the water goes through the process of purification, its use can be upgraded to the irrigation field and other applications.

Grey Water Harvesting is a relatively new practice in the institutional buildings. It is a practice that calls for a lot of regulatory implications as opposed to rainwater harvesting. Grey Water, unlike other renewable sources of water, contains some chemical and biological contaminants.

These contaminants may contaminate the water into black water that may lead to awful smell with an implication of being a health hazard if maltreated.

Advantages Associated With Grey Water Harvesting

There are many benefits associated with the use of grey water. Embracing the grey water system attracts the following pros.
It is Economical:
If your household bears a water meter, your reduction in water usage translates to a reduction in the bill. Good news is that the costs of purchase and installation of a grey water system are close to nil. It does not require huge initial investment.

After the purchase and installation of the system, you are bound to have other benefits flowing in. Although it depends on how much water you use or the frequency of use, there is a considerable reduction in water usage when the Grey Water system is imposed.

Using this system, the usage is cut by a close to a half the amount used otherwise. It is one of the best means for saving water.

Natural resource protection

There is a significant growth in population across the globe. This is not without the southern African part. The ever-rising population and industrial growth rates cause the strain in our water resources as well. Therefore, everyone has a role to play to shun the epidemic.

Each can cultivate a sustainable relationship with our environment. This can only be possible if we economize on the use of water. Grey Water usage is a brilliant way of ensuring that the generation to come won’t lament concerning the water issue.

Reduction of power consumption

Looking beyond the surface benefits, you realize the long run indirect benefits. If you consider how basic water treatment process flows, you will appreciate the efforts of Grey Water. Treatment of water involves a rigorous process that makes use of many pieces of electrical instruments.

Reduce sewage

Not only does the grey water reduce the demand for water supply, but also in septic wastage. Reusing the water leaves less of in flowing into sewage as septic flow. You cut the load in the septic wastewater. The reduction translates to the septic system handling less of the effluent.

The system will, therefore, be in a position to handle less waste in extended shelf life. There are minimal chances of servicing the sewage. Additionally, as you reduce the sewage amounts, you will tend to be charged fewer coins. Therefore, by lowering the disposable flow of water, you will subsequently end up with more savings in your pocket.

Grey Water Harvesting Solves soil problems

Any garden will require the appropriate amounts of sunlight, soil and adequate water for it to bear fruits successfully. According to soil science, different varieties of plants will thrive in their different environments.

For a garden to bring forth the best, it must be growing in its most natural setting. Just as plants require these conditions during their growth period, dry soils crave for more water.

An alternative to sprinkler systems is the use of Grey Water Harvesting system. Since they are equipped with a sieving system, the household water flows through the pipes into the gardens to wet the thirsty soils. The water offers a variety of benefits to the plant from the health of the plant to water conservation.

Little usage of water

The undeniable benefit of grey water is the economical use of water. It is estimated that an average household will use between 300 and 400 liters of recyclable water on a daily basis. Also, an average suburban garden uses about 35% of domestic water for daily usage, stemmed from the grey water.

The level can rise up to 60% if one does the recycling to the best of his/her level. Grey Water, therefore, saves water usage in the era when water resource has been categorized as scarce.

Enhances More Savings With Grey Water Harvesting

The savings that are generated when the use of grey water is imposed gets higher. Finances that are given out for pure sourcing water for the irrigation purpose become lessened in the overall process.

Reusing the grey water keeps it out of the septic system. As a result, the chances of polluting water bodies become narrow. The finances that could have been used in treating the polluted water are saved as well.

Reusing of Grey Water for irrigation reconnects urban inhabitants and the garden fields to the natural water cycle. Reusing Grey Water results in a dramatic drop in the demand for fresh water. This as well contributes to savings.

Nutritional Benefits to Plants

The soap residues can provide sulfates and nitrates that are components of garden fertilizers. Researchers say that these compounds are very beneficial to the garden in comparison to tap water. The water can be used in the vegetable gardens.

However, it is not recommended to use the water two weeks before harvesting. These nutrients become crucial at a point when more food is needed in a drought; at such a time like this. It is satisfying to realize that plants are fed with nutrients that eventually benefits human. The grey water aids vegetation flourish in the event when fresh water may not be available.

Process of Grey Water Harvesting

Harvesting of Grey Water is a simple process when broken down into stages. The process has several systems that are synchronized into one operation. It entails both biological and chemical processes. The following methods work in compliant with each other to bring the overall result.
Water from showers and sinks is collected via a plumbing system. The piping system is separate from the one that connects the toilets. The collected water is then diverted to a collecting tank. Through filtration, some large particles are eliminated.

Chlorine and other oxidizing agents are then added to the water inside the tank. These chemicals are geared towards lessening the level of bacteria in the water.

After a given period, the grey water is diverted through pumping system to a filtration skid. If commercial systems are the ones to be used, a self-cleaning disk filter serves the purpose. Larger particulates are eliminated here.

The preceding stage makes use of a multimedia filter that removes smaller particles. The system is adjusted with filters that minimize maintenance. This is done through an automatic backwash step.

Here, all the debris get instant flushing ending up in a sewer system. The backwash also rearranges the multi-levels of filtration media.

The last step is the “polishing” stage. The activated charcoal makes the water clear devoid of any impeding odor. The treated Grey Water is now ready for reuse.


To keep off organisms like bacteria, algae, viruses, and other contaminants, it is necessary to sterilize the water in the tank. This is made possible through chlorination and use of UV sanitation method. There is a possibility of contaminants remaining in the water despite the process mentioned above.

Therefore, chlorination is done to maintain the entire system clean. Addition of chlorine chemical is the most effective method to achieve this.
Some Grey Water Harvesting systems make use of UV sterilizers to achieve the purpose. The ultraviolet sanitation exposes the water to a given wavelength of UV light. The light obliterates the organisms DNA. Expert is needed to maintain specific and sufficient radiation.

It is an advantageous method that makes use of zero chemicals to render the organisms sterile. It is a less expensive method as compared to other methods.


Storage of Great water is necessary especially when the demand for the water shoots high. It is also determined by factors such availability of space, the volume of Grey Water treated, and turnover frequency.

It is necessary to have the tanks pre-mounted on a higher level, slightly above the ground level. Storage enhances the efficient supply of water throughout the garden in the event of irrigation.

Enough storage is necessary to have enough for the dry spell, especially when rains become irregular. The storage will be of great use especially in a time like now where the place is facing a severe drought. There are many tanks on the market from the JOJO tanks and a good few other suppliers. Our advice is to look around for competitive pricing on the water tanks.

Application of grey water

For a grey water system to move, a repressurization system is required which moves the grey water to the restrooms and other areas within the building. Low-cost pumps are also available to move the water from the tanks to the required areas in the home or garden.

A commercial system involves the use of pump skids that are duplex. The system has two commercial grade pump twins that operate in tandem. Each pump is designed to work at the rate of 70% of peak demand.

In the event of high demand, the system works alternately. When the demand is not wanting, the two identical pumps alternate in the course of operation.

Future of grey water

Nothing is more useful among all living things than fresh water. Unfortunately, it is becoming a limited resource. It is estimated that global fresh, natural water is subject to lower Research conducted by Scientific American Magazine, the ever-growing population in an equal change in climate will create more water scarcity.

The developing countries are not an exemption of the estimated far and wide scarcities. The rapid growth of population will demand more food supply. The food supply is highly dependent on water. The human needs the water the more. To offset the shortage of food supply, there will be a need for rapid growth of the water-intensive agricultural system.

For these systems to continue supporting the sector, they will call for more water. Therefore, grey water will be a need that will require constant supply in the future.

The takeaway

The use of Grey Water Harvesting has become increasingly popular. There are countless benefits associated with the grey water system. It comes as a remedy to the economic system and natural environment conservation.

The technological means of installing the system is not complex either. In a rapidly growing city like Cape Town, it is a critical system to sort out water issues as well as drought endemics. The future of grey water can be viewed in a broader funnel end.

It is a means that will eliminate some problems associated with the food shortage as well as the natural ecosystem.

Overall, with water being a scarce resource across the globe, the use of Grey Water Harvesting acts as an excellent way of making economic use water. It is an excellent way for anyone who is looking forward to moderating their footprint. In fact, this is a system that will help the earth, your household and your wallet concurrently. In fact, grey water should never be used for a potable purpose like cooking or drinking unless it is thoroughly purified.