Water systems
MATERIALS ENCYLOPEDIA
Water systems INTRO:
For most of human history, we have spent a huge amount of our time collecting, moving and storing water, mostly with manual labor. There are still many places in the world where turning a tap to receive an endless supply of potable water is not the norm. And there is good reason that we should no longer consider water to be the cheap, disposable resource we’ve come to expect at every faucet.
Water issues are complex. In the simplest terms, we tend to consider the source, quality and quantity of water that comes out of taps and faucets in the home. These are obviously very important issues, and there are significant concerns on all three counts that help to direct more sustainable choices.
What we rarely consider are the high energy costs that accompany water. Figures for the province of Ontario, Canada, for instance, show that “water and wastewater services together represent a third to a half of a municipality’s total electricity consumption,” and that “municipalities, largely responsible for the provision of water in Ontario, have been reported to consume more electricity than any industrial sector outside Pulp and Paper.” This does not take into account the energy used for private residential and commercial wells or industrial water pumping. Conserving water, when seen in this light, is about more than reducing the use of a valuable natural resource — it is also inherently about energy conservation.
In combination, these issues make smart thinking about water systems a must for anybody interested in more sustainable building, as the dividends for lowering water use are double. The good news is that there is still a lot of “low hanging fruit” available, making significant water savings relatively easy.
Water systems are highly regulated in our building industry. Sources of water are subject to many levels of government jurisdiction that will regulate how, when and where water is extracted. All components of a drinking water system must meet the requirements of codes. In some regions, a drinking water system may need to be designed by a licensed professional, with each component specified and inspected.
What follows is an overview of available options when it comes to water systems. All are feasible, but not all are prescribed by building codes. They may be combined in different ways to meet specific situations, according to need, climate, personal preference and local regulations.
Water sources
Water systems begin with a source of water that can be accessed for use in the home. There are really only four options for sourcing water; depending on your location you may be lucky enough to be able to choose from more than one, but often there are only one or two feasible possibilities.
Individual vs. municipal supply
All water sources may be used for a single-family residence, a neighbourhood or an entire region. If your home is located in an area that is serviced by a municipal water system you may not have any choice regarding the source of the water. Some municipalities will not allow private water systems to be used within their boundaries, so be sure to check local codes before pursuing any alternative to the municipal supply.
System components
- Foot valve and screened intake
- Tubing, buried to avoid freezing where applicable
- Land-based or submersible pump
- Pressure tank, if required
- Filtration as required
How the system works
{28 surface water illustration}
Water is drawn directly from a lake, river, stream or pond. This system is used for individual residences and entire municipalities.
Water is drawn from the source as required, using the natural capacity of the water body as a storage medium.
Water quality issues
Surface water is vulnerable to a wide range of natural and human contamination, and will almost certainly need extensive treatment in order to be potable.
Assessing water quality can be difficult, as the water will vary greatly in quality depending on season, weather events, human influence and natural cycles and issues. Before choosing to use a surface water source, determine the origin of the water body and find out what kinds of activities happen upstream from your intake, in particular industries, sewage treatment facilities and major highways, any of which can introduce contaminants. If the water body is subject to seasonal flooding and/or drought, this will also affect quality by introducing new contaminants or concentrating existing contaminants.
Surface water should be tested regularly, as levels and types of contamination will change.
Pump options
Submersible, jet, diaphragm and hand pumps can all work with the low heads that are typical with surface water collection. Certain rivers and streams may be suitable for the installations of a ram pump.
Environmental impacts: Low to High
Residential use of surface water does not typically have negative impacts on surface water sources. Large municipal systems can draw quantities significant enough to change overall water levels in some surface sources and create changes to ecosystems.
Material costs: Low to Moderate
Systems rarely require deep digging, but distance from water source will affect cost. Low heads require less expensive pumping options.
Labor input: Low to Moderate
Surface water systems are relatively easy to set up. In cold climates, water lines will need to be dug below the frost line.
Skill level required for the homeowner
Operation— Easy
Once installed, most surface water systems operate automatically. Proper inlet positioning should ensure a supply of water as long as levels remain within expected norms.
Maintenance — Easy to Moderate
Inlets should be inspected and cleaned on an annual basis at minimum. Pumps have a finite lifespan and will eventually need replacing. Pumps positioned and plumbed for easy access and removal will greatly reduce labor time when issues arise.
Sourcing/availability: Easy
Surface water collection systems are common, and components and installation professionals will be easy to access.
Future development
Long established as a viable water source, the components of a surface water system have been well developed and are unlikely to change dramatically.
Resilience
Surface water sources are susceptible to climate change, which can raise or lower water levels. Changes are likely to happen at a pace that will not catch the owner of a surface water system by surprise, but may require adaptation.
It is possible to operate a surface water system with little or no energy using hand- or bicycle-powered pumps.
Tips for a successful installation
1. Choose an inlet point that is not too close to the bottom or the top surface of the water body, where contaminants tend to be more concentrated. Keep the inlet in a position where plant growth will not interfere with intake.
2. Attach the inlet securely so it is not dislodged by fast-moving water or human or animal activity.
3. In regions with freezing conditions, the inlet must be below the expected depth of ice coverage and must be routed to the house in a way that will prevent exposure to freezing.
4. Be sure that the installation does not interfere with existing fish or animal habitats.
System components
- Well casing (concrete for shallow wells, metal for deep wells)
- Submersible pump
- Tubing, buried to avoid freezing where needed
- Pressure tank
- Filtration as required
How the system works
There are two types of wells, but both operate on the same principle. An underground aquifer is accessed by digging or drilling an intake point into an area with sufficient flow to provide the required quantity of water.
Dug Wells — These wells tend to be shallow, between 3–12 meters (10–40 feet). A hole is excavated (by hand or machine) and the sides shored up and retained by sidewalls. Water in the ground collects inside the well and is pumped or lifted from this reservoir.
Drilled Wells — Used to access deep aquifers (between 12–120 meters / 40–400 feet), these wells are mechanically drilled (through any type of soil or rock) until sufficient water has been reached. A metal well pipe is then fitted into the hole and water from the aquifer fills some portion of this pipe. A submersible pump is lowered into the pipe and sits in the water.
Water quality issues
Drilled wells may supply potable water with no need for treatment. Deeper wells tend to have fewer issues with bacterial contamination, but are often rich in mineral content. Depending on its composition, the rock around the aquifer can affect the odor and taste of the water and the interior of the piping can suffer buildup of mineral scale. Treatment may be required to remove mineral content.
Drilled wells may be contaminated by sources far from the intake, especially as the movement of underground aquifers is not well mapped and water can travel long and circuitous paths. On the plus side, deep wells tend not to be affected by seasonal changes, and a well that provides clean water is likely to continue to do so unless new human activity somehow affects it.
Pump options
Submersible pumps are used for all deep wells. Shallower wells (under 30 meters / 100 feet) may be fitted with submersibles, or with a land-based jet, diaphragm or hand pumps.
Environmental impacts: Low to High
Single-family dwellings are unlikely to affect water levels in underground aquifers, but municipal wells with heavy draws can have serious impacts on the quantity and quality of water.
Material costs: Moderate to High
A significant amount of digging or drilling is typically required. Cost will be directly proportional to well depth. More expensive pumps are required to overcome high heads.
Labor input: Moderate
Digging a well by hand is extremely hard work and is rarely done today. Backhoes are used to dig shallow wells and purpose-built well-drilling rigs are used for deep wells.
Skill level required for the homeowner Use
Operation— Easy
Once installed, most well water systems operate automatically.
Maintenance — Easy to Moderate
Wells may need maintenance to break up mineral scale that can affect water flow into the well. Frequency will depend on the mineral content of the water. Pumps have a finite lifespan and will eventually need replacing. Removing a deep well pump can be difficult.
Sourcing/availability: Easy
Wells are common, and components and installation professionals will be easy to access.
Future development
Long established as a viable water source, the components of a well water system have been well developed and are unlikely to change dramatically.
Resilience
Groundwater sources are less susceptible to climate change than those on the surface, but it is difficult to predict potential changes to any given aquifer.
It is possible to operate a well water system with little or no energy using hand- or bicycle-powered pumps, but only possible to dig shallow wells by hand.
Tips for a successful installation
Sub-surface water can be difficult to locate. In some regions, a well may be dug or drilled anywhere with a high probability of finding water, but in many areas there is no guarantee that water will be found. In some cases, several attempts may need to be made to locate a suitable aquifer. Dowsers and experienced well-drillers can help, but finding water can still be a matter of chance.
System components
- Roofing of suitable material for collecting potable water
- Eavestroughs/gutters with screen covering
- Downspouts
- First flush diverter
- Storage tank
- Land-based or submersible pump
- Filtration as required
How the system works
The roof area of a building is used to capture rainwater via eavestroughing. Downspouts typically carry the water to a first-flush diverter, which directs a quantity of water from the beginning of a rain event away from the tank to prevent contaminants on the roof from entering the tank. The water is directed to a storage tank where it is held until required for use.
Water quality issues
Rainwater is typically very clean, unless contaminated by particularly heavy air pollution or toxic dust on the roof. Rainwater is distilled water and therefore has very low mineral content. Unless re-mineralized, it can have long-term health effects if it is the main source of drinking water. Low mineral content in the water can also cause leaching of mineral content from piping, which is of special concern if the piping contains fittings that may have lead and/or zinc content.
Re-mineralizing of rainwater can be achieved using a simple sand filter, or by partially filling the storage tank with sand and gravel.
The storage tank is susceptible to algae growth under the right temperature and light conditions. Dark, cold tanks are unlikely to support algae.
Pump options
The storage tank may be fitted with a submersible, jet, diaphragm or hand pump.
Environmental impacts: Negligable
Rainwater catchment systems are a very low-impact means of collecting water, making use of natural rainfall events in a way that has very little impact on surface and groundwater levels and quality.
Material costs: Low to Moderate
A storage tank will be the most expensive component of the system, and prices vary depending on tank material and capacity. NSF certified gutters, downspouts and other accessories may be more expensive than uncertified versions.
Labor input: Moderate to High
All the components of a rainwater harvesting system are straightforward, but there are more components to install than with other systems.
Skill level required for the homeowner Use
Operation— Easy
Once installed, most rainwater systems operate automatically. Homeowners will need to monitor water level to ensure use does not outstrip supply.
Maintenance — Moderate
Eavestrough, mesh covering and first-flush diverters need to be inspected regularly to ensure there are no leaks or blockages. The storage tank should be inspected at least annually to ensure it is clean and operating properly. Pumps have a finite lifespan, but are easy to access in most systems.
Sourcing/availability: moderate to difficult
Surface water collection systems are common, and components and installation professionals will be easy to access.
Future development
Rainwater harvesting is growing in popularity. In some areas it is the most feasible means of collecting water, and codes and standards being developed in these jurisdictions are helping to make systems more acceptable elsewhere. The low-impact, low-energy nature of these systems will increase their market share as water security issues become more prevalent.
Resilience
Climate change may make rainfall levels unpredictable, with some areas receiving more than normal and others experiencing longer periods of drought. The feasibility of rainwater harvesting will depend on these factors, though any area that can support human habitation can use rainwater catchment.
It is possible to construct and operate a rainwater harvesting system in a low- or no-energy manner.
Tips for a successful installation
- Install a roof sheathing that is suitable for rainwater harvesting. It should be an inert surface that does not impart any chemical content to the water.
- High-quality eavestrough is crucial. Leaks in the eavestrough or downspouts will rob the system of water and may introduce contaminants.
- An eavestrough mesh should be installed, and the finer the mesh the more contaminants it will keep out of the system. High-quality stainless steel mesh is ideal.
- A good first-flush diverter helps to keep contaminants out of the tank. In cold climates, be sure the diverter is not prone to damage from freezing.
- Install a tank that may be accessed for occasional cleaning.
- With properly sized storage tanks, most regions that can support human habitation can have functional rainwater harvesting. In dry areas, it is important that catchment area and storage capacity be sized to take advantage of all seasonal rainfall events, so that the maximum amount of water can be stored.
- There are established formulas for estimating average annual rainfall and calculating catchment from a roof area that can be used when sizing storage tanks and roof size.
How the system works
Desalination can be undertaken at a residential level, which would favor membrane or solar technologies, while municipal facilities use large-scale distillation or membrane plants.
In 2009, 14,451 desalination plants operated worldwide, producing 59.9 million cubic meters of potable water per day.
There is a great deal of research and development going into improvements in existing technologies and exploring new ways of achieving desalination. Low-temperature thermal desalination and thermoionic technologies are both promising. Many low-tech, homemade or small-scale systems have been invented and are in use around the world at a residential scale. Small desalinators typically work by slowly processing water, which is then stored for use. A storage tank is therefore an integral part of the system.
There are several methods for desalinating seawater or brackish groundwater:
Distillation Methods-
These methods use high amounts of heat to separate salt content from the water.
- Vapour Compression
- Multi-stage flash distillation
- Multiple-effect distillation
Membrane Process
These methods use pressure and a membrane capable of capturing salt while allowing water to pass through.
- Reverse osmosis
- Electrodialysis reversal
- Nanofiltration
- Membrane distillation
Solar Desalination
- There are many variations of solar desalination, but most rely on evaporative processes using the sun’s energy
Water quality issues
Desalination can provide high-quality water requiring no further treatment.
Pump options
Most desalination methods are surface-based, requiring low-head submersible, jet, diaphragm or hand pumps.
Environmental impacts: High
Desalination offers a great deal of promise as a way to reduce demand on the planet’s limited fresh water resources, especially in the world’s densely populated coastal regions. However, current technologies use a lot of energy in the desalination process, either to produce heat or pressure, and are currently a strain on fossil fuel resources and a significant contributor to greenhouse gas emissions. A lot of effort is going into reducing the energy costs associated with desalination, and large plants are often being twinned with other industrial processes to make use of waste heat (nuclear power plants can be used in this way) to help reduce these impacts. Unless some of the promising new technologies are brought to market affordably or significant technological advances are made, increasing demand will offset any minor improvements in efficiency and will not reduce impacts.
On a small, residential scale in a sunny climate, solar energy can often be used to desalinate enough water for a household via both low- and hi-tech means. These can be all solar, or a combination of solar and other sources of energy.
Regardless of the scale of a desalination system, the resulting brine can have environmental impacts. The highly concentrated levels of salt that are the by-product of desalination cannot be returned directly to water or soil without having potentially serious implications, as raising the salt level in the ground or in a water body can alter pH and kill off plant and animal life.
Material costs: high
Labor input: Moderate to high
Installing a home-scale desalination system may involve the on-site creation of an appropriate solution, and may take time to assemble and fine-tune.
Over-the-counter systems have relatively short installation times.
Skill level required for the homeowner Use: Easy
Operation— Moderate
Once installed, most desalination systems operate automatically. Homeowners will need to monitor water level to ensure use does not outstrip supply.
Maintenance — Moderate-difficult
There is regular maintenance to do on a desalination system, including checking and cleaning intake point, cleaning pipes, filters and membranes (where used) and properly disposing of brine.
Commercial systems will have a prescribed maintenance cycle that should be adhered to.
Sourcing/availability: Moderate-difficult
Commercially produced desalination systems are relatively easy to source, especially through marine supply outlets and directly from water purification manufacturers.
There are instruction manuals and online resources for those wishing to build their own desalinator. Most or all of the parts required will be available through plumbing supply stores or water purification outlets.
Future development
Large-scale desalination is the subject of a great deal of research and development by nations that rely on this method to provide water to their citizens. With water security a national priority in many parts of the world, expect rapid development and deployment of this technology.
If large-scale developments provide new solutions that are appropriate for small-scale desalination, the trickle-down effect will help homeowners. A lot of experimentation is happening among those using homemade desalinators, and this may also bring refinements and developments that make for better owner-builder solutions and home-scale commercial systems.
Resilience
For anybody living in a coastal region with a limited or uncertain fresh water supply, a desalination system is an important element in being resilient. Home setups that require little or no energy will ensure clean water supply independent of fossil fuels or climate changes.
Tips for a successful installation
1. Each commercial desalination method will have its own particular requirements. Follow manufacturer’s installation instructions.
2. For homemade systems, carefully consider the water needs of the home and the cycle of use and size storage capacity and output of the desalination system to meet those needs.