Rainwater harvesting entails capturing and diverting rainwater to homes or storage sites for consumption, domestic and industrial use. It has several advantages. First, it provides an alternative to conventional water supply methods and systems like piped water from municipal councils or bore holes. Furthermore, it supplements water demands placed on standard water supply systems. Secondly, it prevents most of the negative aspects associated with rainwater such as soil erosion. Lastly, the water harnessed from rainwater harvesting is generally considered clean and can, therefore, be used in almost all applications that utilize water.
Components of rainwater harvesting systems
Rainwater harvesting systems vary in nature and technology. Nevertheless, there are components common to all water harvesting systems from the design standpoint. This includes a system of capturing the rainwater and channeling it away from the capturing point, a system of storage, and a system of treating the water to ensure it’s safe for use. Treatment of water is also done to reduce hardness that is usually associated with rainwater. Capturing and conveyance systems usually use an elaborate system of pipes and storage tanks.
Reverse Osmosis, water filters, water softeners and other chemicals are used in the treatment of the water. Read the following detailed discussion about the various rainwater harvesting components.
Water capturing, conveyance and storage
The basic requirement for any rainwater harvesting system to be used is low permeability and a slight gradient. This ensures that there is no accumulation of debris on the capturing device. Gutters, in addition to downspouts, can be used for this purpose. In conveyance systems, aspects such as rusting should be put in mind when selecting or designing a conveyance system. Even though it’s expensive in terms of money, galvanized iron pipes are generally recommended. A cheaper alternative to this is PVC pipes. During storage, modern storage tanks are suggested instead of traditional ones. What is more, an ideal cover for the storage tanks is advisable to ensure there is no water contamination.
Water filters and water filtering methods
Water filtering methods attempt to remove unwanted particles from harvested rainwater. The materials are responsible for the harmful impurities. The most basic water filtering methods are sedimentation, use of heat and light separation. Sedimentation uses gravitational principles to settle particles in water at the bottom of sedimentation tanks. This then facilitates their removal. Heat use is mostly through boiling to kill all unwanted pathogens in water making it safe for drinking. Sometimes the light is used. The ultraviolet rays of sunlight are harnessed to kill unwanted bacteria in the water.
Chemical methods of water filtering are more popular nowadays due to their effectiveness and applicability in large-scale situations. Some of the common chemicals used in these types of water filters include chlorine, bromine, iodine, hydrogen peroxide, and lime. Chlorine is used in municipal water systems and is preferred because it is cheap and effective. It can also be bought in small quantities for treating rainwater harvested at homes. Bromine is a cheaper alternative to chlorine. Even though not popular, iodine is equally effective in killing harmful pathogens in water. Lime and hydrogen peroxide are mostly used to get rid of water hardness.
Water softening methods
Water softening involves the removal of mineral elements from the water. The elements include calcium and magnesium, which are responsible for the hard properties of water. Several water-softening methods are inexistent today. The basic principles they use is to reduce the quantities of calcium, magnesium and other metal ions from the water. The most common of these water-softening methods is the use of lime. This method takes advantage of the chemical properties of lime that enable it to react with metal ions. The lime is added to the hard water thereby softening it. The resulting water is more compatible to soap.
Another chemical method used in water softening is the use of recharged resins. Sodium chloride and sodium hydroxide are used in this process to replace the magnesium and calcium ions in the water solution. A more popular method used in water softening is distillation. The limitation to this method is the cost implications. The latest technological intervention with respect to water softening is reverse osmosis. This method uses the scientific principle of osmosis to remove metal ions from water. Just like in any process of osmosis, a semi-permeable membrane is used to filter out molecules larger than water particles. Rainwater is pushed through the membrane in order to separate the impurities. The main limitation of this method is the recurrent need for membrane replacement and the fact that it can only be applied in very specific instances.
Electronic methods of water softening have emerged in modern times. The methods, however, do not remove the metal ions from water. Instead, they attempt to reduce their non-attractive properties. Softened water is used for washing clothes, bathing, and hair cleaning. Showering with hard water leaves the skin looking rough. Also, it makes the hair feel dull and hard. Therefore, water softeners are essential to eliminate such problems.
Summing up, rainwater harvesting should be considered as an alternative to conventional water provision methods like municipal water supply. The basic components of a water harvesting system include; a system of capturing, conveying and storage of water, together with a good system of water treatment. Water treatment involves reverse osmosis or water filtering, as well as water softening. All of them attempt to remove impurities and other harmful pathogens in water. It also helps in reducing the level of hardness in water.
The water treatment methods can be grouped into physical, chemical and electronic. Physical methods like the use of water filters are more popular. On the other hand, Chemical methods like the use of chemical water softeners are less popular and mostly used in large scale. Latest developments, nevertheless, have solved this problem by coming up with chemical solutions for small-scale applications.