1. What is Rainwater Harvesting System?
What is Rainwater Harvesting System? As we know water is a very precious and valuable resource for all of us. For all living things, water is the most important natural resource. On earth, we can’t imagine life without water. All human productive activities need water.
Rainwater Harvesting is the combination of two words mainly ‘Rainwater’ and ‘Harvesting’. Generally, the meaning of Harvesting is to collect or gather something. ‘Rainwater Harvesting’ is mainly the process of collecting rainwater for future use.
Collection and use of rainwater have been a part of human history for thousands of years. The collection and use of rainwater have diminished due to cost reduction in groundwater drilling and the increased prevalence of municipal centralized water systems. In developed countries, nearly all communities treat water as an infinite resource or as a liability.
So governments, municipalities, and individuals need to realize and start capturing and storing rainwater is critical to sustainable, economic, and resilient hesitation.
As we know water is a limited resource. Water needs to be conserved in many ways like the forest or in an open area. The rainwater seeps into the ground and recharges the water table.
Due to vast urbanization and increasing population, more areas are being occupied by roads and concrete buildings leaving less space for rainwater to seep.
Rainwater runs off from catchments like rooftops, paved areas, and the bare ground is collected and stored. The conservation and utilization of rainwater help in preventing water runoff, evaporation, and seepage.
In rural areas, the rainwater quickly flows into the river and dries up soon after the rain stops. If rainwater is allowed to stay, it can help to recharge the water label. Rainwater harvesting provides an option for conserving the rainwater.
Rainwater harvesting is actually a technique by which rainwater is collected and stored for later usage. Rainwater harvesting helps us to increase the capacity of water available.
The growing population, various industries, and agricultural practices on earth need a lot of water. We need to think about a variety of waste to save and conserve our water resources for the future.
One of the very important preventive measures for the conservation of water is rainwater harvesting. Basically, water comes to the surface with rain. However, it gets collected in rivers which ultimately flows into the ocean. It means that the usable water is lost in the ocean.
Rainwater harvesting is unique from any other water supply perspective and challenges the largely centralized approach to water supply and its use. This brings about much uncertainty and unknown which leads to a widespread hesitancy regarding the implementation and use of these systems.
From a stone water management perspective, rainwater harvesting systems are the only best management practices that serve an important supplementary goal of water supply.
Rainwater harvesting systems contain more moving parts than any other stormwater BMPs (Best Management Practices) currently used. Together these factors greatly increase the design complexity of the systems.
The number of project stakeholders and the necessary maintenance requirements does generate hesitancy within the stone water industry to exploit the full potential of these systems.
Rainwater harvesting and conservation aim at optimum utilization of the natural resource that is rainwater which is the first form of water. As we know in the hydrological cycle and hence is a primary source of water.
The rivers, lakes, and groundwater are the secondary sources of water. In the present time in absence of rainwater harvesting and conservation, we depend entirely on such secondary sources of water.
Rain is the ultimate source that feeds to the secondary sources of water. Due to this the value of this important primary source of water must not be lost.
Rainwater harvesting and conservation means to understand the value of rain and to make the optimum use of rainwater at the place where it falls.
All the forms of life on the planet depend on water to survive. It stated simply that water is the basis for all life on earth.
As profound as our dependence on water is, there is an equally profound lack of knowledge concerning Where water comes from and how it is based and most efficiently used as a public and private resource.
2. History of Centralized Rainwater Harvesting System:
Most conventional water sources include ground water from shallow or deep wells, rivers and lakes. Humans depend on the sources and their re-plan easement via the hydrologic cycle.
Through the input of energy from the sun, water moves from the surface of earth to clouds and again back to the earth surface.
In the hydrologic cycle there is water in constant motion. Population has always grown where there is adequate water. In addition to gathering water from surface sources and waves.
The use of cisterns has been documented in many cultures for capturing rainwater. Large cisterns at canal curves for transporting roof collected rainwater are found in Petra , Italy dating from Roman times .
Adequately constructed by the Romans were also early efforts at providing a centralized water system to a concentrated population.
Sound worldwide including irrigation Strategies for agriculture. Over the centuries small and large communities have continued success and failures in securing adequate sources of freshwater for daily activities.
Centralized systems in use today throughout the developed world provide a standard level of safe treated drinking water through a continuous loop that extracts water from lake, rivers and aqua fire there and then treats and distributes the water to the end-users.
As described in a recent publication on climate change Urban Water systems have evolved into large highly engineered systems in which water is imported from surrounding catchments and equip fires distributed through extensive pipeline networks and used once only.
In the last 100 years with the exponential increase of man made impervious surfaces of the hydrologic cycle has been intercepted and impacted by industrialization and mechanization and population growth.
It is an alarming increase in stop water discharge velocities and volumes are causing a paradoxical shortage of freshwater resources. These are caused not by a reduction of the amount of the water but rather contamination and pollution of the available water due to flood in erosion and sewage.
In many parts of the world many new regulations and policies that promote centralized water distribution are still being encouraged to the exclusion of all other decentralized approaches.
One of the parameters of the economic health of a country is the degree to which centralized drinking water and sewer systems are present.
Many countries that lack functioning centralized water distribution systems continue to look to the developed World as a source of inspiration and technical knowledge.
3. Return on Investment (ROI):
In the past a simple return on investment calculation included the amount spent on the rainwater harvesting system (tanks, pumps treatment and the like) versus the cost of municipal water.
The belief needs to change that water is free and unlimited. That places an intrinsic value on water and it’s inextricable relationship to the built environment.
The cost of municipal water is a key component in calculating the ROI on rainwater harvesting systems is water rates, by and large do not reflect the total infrastructure replacement cost.
Using traditional water is not the best way to measure the cost. There are many infusions of grant money and local options sales tax that are not accounted for in what is charged to the water consumer.
Using causes as the way to measure the ROI of a rainwater harvesting system is an inadequate way of valuing these systems.
New water infrastructure expenses are paid largely by new customers and municipalities by connection fees, impact fees and Bond issues which are not built into the actual water rate.
During an economic downturn revenue is not generated by new customers and must come from somewhere either in the form of taxes or fees for rate hikes to the public.
Now in commercial development stormwater management infrastructure and its associated costs, they are compulsory and increasingly common across a wide array of residential construction.
To a large degree stonewater infrast structure is designed and built to prevent loss of life and property from devising floods resulting from in previous surfaces.
Rainwater harvesting has the potential to reduce the cost of water supply and manage stormwater runoff through the application of a dual-purpose infrastructure.
Whenever in water or storm water can be captured on site for either indoor or outdoor uses some of the effects of impervious surfaces are mitigated.
More water managed on-site equals less water to be managed from the side and downstream. Rainwater harvesting systems reduce flows to an overburdened storm water drainage Network and represent a real savings that is not included in the traditional cost.
Municipalities are beginning to develop policies that encourage storage and treatment of the initial amount for the first flush of rainwater in a storm event in order not to overwhelm existing drainage infrastructure.
There are some additional benefits of reduction of erosion to banks on rivers and streams. The rainwater harvesting systems as part of a stormwater management plan can actually increase the developable area on a site.
The economic and environmental benefits of rainwater harvesting future development projects that include rainwater harvesting systems made become financially and ethically viable.
In conclusion with rising water rates potential water scarcity and new policy directive to improve Urban runoff water quality and quantity current arrow calculations must include the benefits of rainwater harvesting effort then water harvesting systems and hence the resiliency of centralised Water Supply and Drainage systems.
4. Planning for Rainwater Harvesting System:
When planning a rainwater harvesting system the following step should be followed:
4.1 First interview property owners and stakeholders to determine system objective design training and consideration and so forth.
4.2 Research the regulations and permitting processes required by federal state, country and local building codes.
4.3 Research applicable incentives and green building rating systems.
4.4 Present various options of design to the owner or other stakeholders of a property.
4.5 Create an integrated plan for water conservation that starts with a water audit and follows through to the specification of water saving fixtures.
By following these steps, the design professional will find that rainwater harvesting can be achieved as part of an integrated sustainable design system regardless of the scale.
Owners may often wish to take small incremental steps when considering implementing rainwater harvesting for the first time.
Freshwater is one natural asset as a Priority. People use a lot of water for drinking, washing, cooking, and irrigating landscapes.
The use even more water to produce food material products manufactured items such as clothing and to run building the total amount of freshwater consumed by an individual business or nation to produce goods and services is known as the water footprint of that individual business .organization in an effort to reduce our collective freshwater footprint.
5. Scopes of Rainwater Harvesting
Rainwater harvesting may be defined as the use of rainwater before it joins the water courses from where its collection is either limited or costly.
In any building Rainwater harvesting implies the collection of rainwater that falls on a building or its premises as well as the use of the collected rainwater.
In the Rainwater harvesting system, rainwater is intercepted, diverted, stored for future use, and distributed into the ground before draining the excess rainfall.
Rainwater-harvesting technology in a broader perspective, is applied into two major sectors:
- General-purpose use
- Recharging groundwater
5.1 Rainwater for General-Purpose Use
There is a need for water for a variety of uses in building of different occupancies, starting from drinking to cutting metals.
It is assured that in all purposes of use of water, rainwater can be used for the same purpose subject to the proper treatment of the rainwater needed for that purpose. General purpose use of rainwater in a building involves a wide range of functional techniques, which are discussed.
5.2 Rainwater for groundwater recharging
When buildings must be built in an area that experiences acute shortages of water particularly in areas where the source of water is predominantly groundwater over-extraction of groundwater might cause various hydro-geological problems. Rapid lowering of groundwater level and its depletion are major concerns.
6. Functional Techniques In Rainwater Harvesting:
For harvesting of rainwater, a series of jobs must be performed. Appropriate techniques must be applied in each job; otherwise, the objective might not be achieved of rainwater harvesting.
6.1 Planning Aspects of a Rain-water harvesting System:
Generally, a reinforced concrete building is supposed to have a maximum useful structural life of approximately 75 years. Particularly the water-environment scenario of the environmental scenario might be changed in this long span of life. Some alternative options might be required for the building of a water management system.
After construction of any building, the incorporation of a rainwater-harvesting system, as a supplemental water-management system, will be difficult but not impossible.
While preparing the architectural drawing of a building, planning for the incorporation of rainwater-harvesting elements must be performed, in light of the following planning perspectives.
First, synchronizing the harvesting8 system with the normal water supply and drainage system, then positioning the components of the rainwater-harvesting system, and then incorporating the provisions for maximizing collecting in case of shortage.
During the planning approach, to develop a well-planned rainwater-harvesting system in a building, the following jobs must be performed:
- First, identify the main purposes requiring the use of rainwater
- Plan the catchments
- Plan the collecting system
- Plan the manner of storing and assign the storage system
- Plan the conditioning system
- Plan the supplying system
- Plan the location of the recharge structure.
6.2 Design Aspects of a Rainwater-Harvesting System:
The main components of the design aspect of rainwater harvesting involve optimum sizing. The main objectives of designing a rainwater-harvesting system are to ensure the following:
- Run the system efficiently
- Keep the system always safe from pollution or contamination
- Save energy
The important steps in designing the system include the following:
- Estimate the amount of rainwater to be collected and stored
- Size the catchment area needed
- Design the collection and drainage pipes and their appurtenances
- Design the pumps
- Design the tanks, e.g., storage tanks, sedimentation tanks, etc.
- Design the filter units
- Design the recharge structures.
6.3 Construction Aspects of a Rainwater-Harvesting System:
The construction aspect of a rainwater-harvesting system focuses on the following objectives:
The main jobs to be performed while developing a rainwater-harvesting system in a building include the following objectives:
- Earth work for underground construction of storage tanks, laying pipes, etc.
- Collect drain pipe, fittings and installation
- Supply pipe fitting and installation
- Install tanks, pumps and accessories
- Construct or install a treatment or conditioning system.
6.4 Maintenance Aspects of a Rainwater-Harvesting System:
The following aspects of maintenance of the rainwater harvesting system must be achieved to ensure sustainability of the rainwater-harvesting system.
- Acceptable hygienic conditions
- The smooth functioning of the system
- Longer life.
Maintenance of the following components of the rain water harvesting system must be maintained at regular intervals with a view to achieving the above-mentioned objectives.
- The catchments
- All pipes and accessories including its inlets
- Gutters or channels conveying rainwater 4 storage tanks
- Filtering units
- Pumping units
7. Planning approach for rainwater harvesting system:
7.1 identifying the purpose of use :
According to the local building development rules or the regulations, at the onset of planning of the development of any building, codes and permit systems must be envisaged regarding the obligation of installing a rainwater harvesting system for that particular area where a building is supposed to be developed.
Rainwater harvesting should be performed for general purpose use, or for ground water recharging, or for both.
Regarding the objectives, the property or building owner and the concerned stakeholders must be consulted. The constraints and cost of the system to be incorporated for rainwater harvesting systems. All necessary provisions must be incorporated into the architectural planning for the building.
7.2 planning the catchments:
The catchments and the area of catchments to be used should be determined after determining the amount of rainwater to be used for various purposes of harvesting rainwater.
These areas should be kept free from other uses for effective use of the catchments. Finishing material of these catchments must be chosen considering the possibility of containing the rain water to be collected.
7.3 planning the collection:
The next step is to calculate the amount of rainwater, after determining the volume of rainwater to be harvested that can be collected from the catchment. The problem is solved when the water available from the roof is found to be satisfactory.
8. Maintenance approach of a rainwater harvesting system:
Every component must be regularly maintained in the rainwater harvesting system at certain intervals. The major components of rainwater harvesting system for the maintenance requirements are suggested below:
The areas must be swept every month to remove leaves, litter, and dirt from which the rain water will be collected. When the dust or dirt accumulate, the catchments must be washed off with water, thus diverting runoff away from the filter or Storage tank before rain starts. Trees also must be trimmed when required.
Before rain or after heavy winds, gutters must be kept clean by washing out bird droppings, leaves, etc. with water. The cleanliness, alignment, stability, and slope of the gutters must be checked every three months as well as after a storm to ensure their proper functioning.
The slope of water should be checked specially and corrected if any deviation is observed after a heavy shower.
All of the pipes including inlet screens installed for rainwater harvesting must be maintained and monitored in the way gutters should be addressed. The pipe must be checked regularly for leakages and must be repaired when required.
8.4 First-flush device:
For cleanliness, the first flush device must be checked. It should always be cleaned before and after the monsoon rain starts and after every rooftop-cleaning operation.
8.5 Treatment system:
At least once in a year before the monsoon rain begins and back washed after the monsoon rain is over, filters should be cleaned. A chlorine level at slightly greater than 0.5 mg/L and a pH level of 6.5-8.5 must be insured by testing weekly and after heavy rains. To keep it free from scum, the UV light must be inspected weekly.
8.6 Storage tank:
There should be extra care taken in the regular maintenance for the storage for the rainwater harvesting system. The tank must be cleaned before the monsoon rain starts and it must be checked for the development of any cracks or leakages.
The cracks or leakages must be repaired at the earliest possible time. The growth of trees must be checked in case of underground storage tanks, or nearby the tank. The roots that might affect the tank must be cut when necessary.
There must be no gap between the lead and its rim and the lid of the tank must be insured for its sturdiness. The insect screen must be well secured at the end of the overflow pipe.
8.7 Equipment and accessories:
In the rainwater harvesting system, all of the equipment and accessories installed must be checked at least once a year. e.g. pump, valves, etc.
8.8 Water quality:
In stored rainwater, the presence of mosquito larvae must be checked every three months. If rainwater is to be used for drinking purposes, accumulation of the sludge level must be monitored with the same frequency.
If rain water is to be used for drinking purpose an E. coli test should be performed to identify the risk of the bacteriological contamination of the stored rainwater.
9. Prospects of rainwater harvesting:
It is believed that the crisis of water prevailing in particular areas is harvested for mitigating. This is the direct and major implication of rainwater harvesting, but there are various other indirect implications of rainwater-harvesting are also present being installed in buildings. The prospective implications of rainwater harvesting in any building are as follows:
1. Decreases the pressure of using surface and groundwater
2. Decreases the cost of water consumed
3 Increases ground water availability
4.Decreases urban flooding and water logging
5. Harvested rainwater saves energy
6. In the development of energy saving “green” buildings
7. It helps to provide water during any crisis
8. Intervention in adaptation
9. decrease in vulnerability due to climate change
10. Renewable resource that does not pose any negative impacts on the environment
11. Salt-free source of water and its use in ground water recharging decreases salt accumulation in soil.
10. Problems of a rainwater harvesting system:
Rainwater harvesting always not brings prospects in the water management sector. In built environments it has some negative implications in built environments also. Following are some negative implications of rainwater harvesting in building development on surrounding environment.
1. The availability of the rainwater may be limited due to occurrence of long dry spells.
2. Quality of rainwater may not be consistent due to variability in air pollution and other sources of contamination.
3. Regular consumption of mineral free rainwater may cause nutritional deficiencies also.
4. The initial investment cost of harvesting components is relatively high.
5. Regular maintenance and lack of proper operation will restrict the desired output from the system.
6. Storage space may hinder the installation of other building service elements at stable locations.
7. There is extra cost for a separate plumbing system conveying the rain water.
8. Rainwater harvesting may not be agreeable to the owner or developer under compulsion.
9. The over-recharging of groundwater may create problems with underground structures.