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Water Efficiency: Resource Report

Alternative Irrigation Strategies

Irrigation and the watering of lawns in residential areas account for over half of the total potable water consumed across the country. There are alternative strategies in terms of irrigation systems and landscaping practices which can reduce this demand upon potable water supply.

Drip Irrigation Systems

Drip irrigation is an example of an alterative irrigation strategy which uses less water and reduces water run-off and excessive evaporation. Drip irrigation is an underground or slightly above ground tubing system that applies water slowly and directly to the soil. The water is then directly absorbed through the soil and into the roots of the plants.[i] The advantages and results of choosing drip irrigation include even soil moisture and decreased loss of water due to evaporation. Disadvantages include difficult installation for buried pipes and clogging of buried pipes.[ii] There are a wide range of drip systems which vary in complexity and in price. The type of irrigation system is dependent upon the area in which it is to be used.

Controlled/Sensor Irrigation Systems

Even in traditional irrigation systems, such as sprayers or sprinklers, an immense amount of water could be saved if sensor methods were installed. Programmable controllers can be installed to any traditional irrigation system in order for the building occupants to program the system to irrigate during optimal times of the day. These optimal times occur during the early morning hours, when sunlight is not intense enough to induce rapid water evaporation. Sensor irrigation systems are slightly different than controlled systems; they monitor soil moisture, wind intensity and rainfall, and irrigate based upon these readings. Both of these systems can dramatically decrease the amount of water consumed.

Non-potable Irrigation Strategies

In some instances, grey water systems may be installed for irrigation purposes. Several places have code against the use of grey water, which may make it initially a more difficult approach. When using grey water, hoses and sprayers may not be used to irrigate because of the potential to spread pathogens and disease. Drip irrigation systems are often installed, as grey water must be applied directly to the soil. These systems are installed above the soil surface and the soil itself is covered with a layer of mulch. Drip lines can also be installed underground. Grey water should also not be used in gardens where produce is to be consumed.[iii] Additionally, occupants who live on lakeshore property may have the option to irrigate using lake water. SJU currently has a system such as this implemented, which draws water for irrigation from Lake Sagatagan.

Composting Toilets

The SUN-MAR composting toilet , produced by Creative Energy Technologies (CET), is one example of a good composting toilet on the market today. Operating such a toilet is rather simple, and it uses no water. First, a peat mix bulking material and some top soil is added to the collection area of the composting toilet . Excess moisture is removed automatically from the drum into the evaporating chamber through a screen in the rear of the drum. The superb aeration in the Bio-drum ensures an aerobic and therefore odorless breakdown of the compost. When it is time to remove the compost, a flush-like mechanism drops the compost into a finishing drawer. http://www.cetsolar.com/sunmarcompact.htm.

Dry Fixtures and Composting Toilets

Toilets or fixtures that were traditionally used with water, but with recent innovations no longer require water to function. Many of these products, such as waterless urinals, composting toilet s, and natural gas toilets have a large number of restrictions or codes to meet, so in most conventional houses they cannot be installed. According to the Department of Health, the only way to install alternative fixtures or innovations in Minnesota is to get an approval from an administrative authority. In most residential settings toilets are the largest consumers of water; old toilets which use three to four gallons per flush consume nearly 28,000 gallons of water per year (for a family of four). Alternative water efficient toilets (1.6 gpf) use only 14,000 gallons of water. By using efficient toilets, we can conserve as much as 14,000 gallons of water annually.

Grey Water Systems

A grey water system is an efficient type of water system that collects water to be used for both domestic and non-domestic purposes. Basically, water that has been used in the home, except water from toilets, is called grey water. Dish, shower, sink, and laundry water comprise 50-80 percent of residential "waste" water. This water may then be reused for other purposes, landscape irrigation, for example. Perhaps surprisingly, a family of four with a well designed grey water system with nearly all potential fixtures connected will save 30,000 to 40,000 gallons of water per year and in many cases it may be more than this. Each grey water system works differently. For more information about grey water systems and how they function, see www.greywater.net.

Groundwater Aquifers

Groundwater aquifers are underground geological formations which are conducive to the bearing of water. These geological formations are typically wells or springs which are able to yield large quantities of water for human consumption.[iv] Groundwater aquifers contribute to the hydrologic cycle, the cycling of water from earth’s atmosphere to the ground and back again. Rainwater and snowmelt accumulate in the soil and surface water; some of this water percolates through the soil and ends up in underground storage areas, or aquifers.[v] Groundwater aquifers act as reservoirs that contain underground water resources, but they also act as conductors moving water throughout the hydrologic cycle, aiding in movement from surface water to groundwater systems. [vi] Groundwater generally comes from two sources, contained aquifers and shallow aquifers.

Contained Aquifers/Deep Aquifers

These sources of water are removed from the normal run-off and hydrologic cycle.

Shallow Aquifers/Uncontained Aquifers

The majority of the groundwater supply comes from shallow aquifers which are prone to contamination by run-off and other pollutants. Unlike contained aquifers, shallow aquifers are directly connected to the hydrologic cycle.[vii] Minnesota has 14 major aquifer systems, and within these systems there are four geologically specific formations, or types of groundwater aquifers. These aquifers are specific to geological formations found across the state. They include unconfined, surficial drift, buried drift, bedrock, and crystalline bedrock.

Unconfined, Surficial Drift

Located close to the surface of the earth, these aquifers are typically recharged by seasonal changes in rainfall and snowfall. Water percolates the surface and is contained in these aquifers; water also can also reach these formations through inflow from other aquifers. These are similar to shallow or uncontained aquifer systems.

Buried Drift

These are pressurized, contained aquifers which are removed from the hydrologic cycle except when receiving inflow from another aquifer or a drilled well. These are similar to the contained aquifers mentioned above.

Bedrock

These are confined aquifers composed of a variety of sedimentary bedrocks.

Crystalline Bedrock:

These are also confined aquifers, but they are composed of igneous or metamorphic rocks. They generally do not yield large quantities of water, but are important aquifers for areas of the state which do not have alternative sources of groundwater . [viii]

Living Machines

The living machine concept was developed by Doctor John Todd, a Canadian biologist. The living machine uses natural biological systems to treat waste water. The Living Machine® system creates an indoor green house environment and mimics nature’s system of treating water. Living machines can be constructed indoors under a light shelter, in a green house environment, or outdoors if the climate permits. In a living machine system, a series of holding tanks are set up in sequence with one another. Whole ecosystems are created in the holding tanks and biofilters by placing communities of bacteria, algae, microorganisms, snails, fish, and various species of trees together, allowing nature to treat the waste. The tanks all contain species which are able to break down the waste naturally. [ix]

Fig 1. The Living Machine at Oberlin College, Adam Joseph Lewis Center for Environmental Studies

Waterless Urinals

A plumbing fixture which uses no water would have been inconceivable a few years ago. Although these urinals look identical to modern urinals, the way they function is quite different. A special system, known as an eco-trap, allows for the avoidance of using water while avoiding the problems of odor. This system is run completely off gravity and consists of a fluid known as blue seal. This unique liquid is less dense than urine, so urine sinks to the bottom area where it accumulates and is drained. This blue seal liquid removes the problem of odors and is completely biodegradable . For more information call 1-888-NOFLUSH.

Water Efficient Fixtures

Water efficient fixtures have become the future of fixtures and other plumbing products. Great improvements have been made to water fixtures, allowing water to be conserved and used elsewhere, ultimately saving money for many households. Although it is impossible to replace old fixtures, it is important to consider the fantastic products available on the market today when building any sort of structure. Toilets use as little as 1.5 gallons per flush; they once used over 2.5 gallons per flush. Faucets now use as little as 1 gallon per minute of use; in the past they used as much as 2.5 gallons per minute. By making these small changes to fixtures and inventing flow restrictors and automatic, we have made incredible improvements in water efficiency .

Water Efficient Appliances

Appliances that are Energy Star™ approved are a great addition to any building aimed at saving water. Like fixtures, new innovations have come to light recently that greatly reduce water consumption. Dishwashers and clothes washers can consume a lot of water and may be rather expensive commodities if they are not water or energy efficient. Clothes washers are the largest consumers of water in most residential buildings, following toilets. Research shows that families with water efficient clothes washers (25 gallons per load) compared to non-conserving families’ homes with less efficient washers (40 gallons per load) save astronomical amounts of water. The difference is roughly 8,000 gallons of water per year for a family of four. Using water efficient appliances and fixtures is logical, not only because it can save large amounts of money, but also because it is a sensible approach to becoming more environmentally conscious.