Frequently Asked Questions
Drinking Water and Human Health
Q: Are water supplies in urban areas better or worse in quality than those in rural areas?
A: The answer to this is not a simple "yes" or "no". In general, one can say that the quality of water in rural areas is better because these areas are removed from industrial activities, which may result in the degradation of the quality of river water, lake water, or groundwater. There are, however, many exceptions. In areas with intensive agricultural activity, mining, and logging, the impacts on water quality can be severe.
General Water Information
Q: How do we determine water quality?
A: To identify the substances present in a stream or lake, scientists collect samples of the water, of living organisms, and of suspended and bottom sediments. Technicians then analyze these samples in a laboratory with specialized instruments and procedures. Certain measurements such as temperature, dissolved oxygen, turbidity and conductivity can be taken in the field with portable equipment. Today's analytical laboratory instruments – with such high-tech names as "plasma emission spectrometer" (for analyzing metals) and "gas chromatograph-mass spectrometer" (for analyzing pesticides, PCBs dioxins, and other organic compounds) – bear little resemblance to the test-tube and gas burner laboratories of the 1950s. Nowadays the analysis of water and sediment samples detects more substances than a decade ago, partly because there are more substances present in water, but also because of improved analytical instruments and consequently lower detection limits. State-of-the-art analytical instruments can detect down to one part per trillion of some substances – comparable to tracing one thousandth of a teaspoon of salt dissolved in an olympic-size swimming pool.
Q: How do we measure water quality?
A: The quality of water is determined by making measurements in the field or by taking samples of water, suspended materials, bottom sediment, or biota and sending them to a laboratory for physical, chemical, and microbiological analyses. For example, acidity (pH), color, and turbidity (a measure of the suspended particles in the water) are measured in the field. The concentrations of metals, nutrients, pesticides, and other substances are measured in the laboratory. Another way to obtain an indication of the quality of water is biological testing. This test determines, for example, whether the water or the sediment is toxic to life forms or if there has been a fluctuation in the numbers and kinds of plants and animals. Some of these biological tests are done in a laboratory, while others are carried out at the stream or lake.
Q: Is water pollution and water contamination the same thing?
A: No, although they are often used to mean the same thing, even in some of the FAQs in this database. Both affect water quality and its use. Pollution is due to the influence or activities of people, where contamination may be natural. Contamination is often used to refer to impurities in water regardless of the source or events that led to the impurities being in the water.
Q: What are the key factors that influence water quality?
A: Many factors affect water quality. Substances present in the air affect rainfall. Dust, volcanic gases, and natural gases in the air, such as carbon dioxide, oxygen, and nitrogen, are all dissolved or entrapped in rain. When other substances such as sulphur dioxide, toxic chemicals, or lead are in the air, they are also collected in the rain as it falls to the ground. Rain reaches the earth's surface and, as runoff, flows over and through the soil and rocks, dissolving and picking up other substances. For instance, if the soils contain high amounts of soluble substances, such as limestone, the runoff will have high concentrations of calcium carbonate. Where the water flows over rocks high in metals, such as ore bodies, it will dissolve those metals. In the Canadian Shield, there are large areas with little soil and few soluble minerals. Consequently, the rivers and lakes in these areas have very low concentrations of dissolved substances. Another factor influencing water quality is the runoff from urban areas. It will collect debris littering the streets and take it to the receiving stream or water body. Urban runoff worsens the water quality in rivers and lakes by increasing the concentrations of such substances as nutrients (phosphorus and nitrogen), sediments, animal wastes (fecal coliform and pathogens), petroleum products, and road salts. Industrial, farming, mining, and forestry activities also significantly affect the quality of Canadian rivers, lakes, and groundwater. For example, farming can increase the concentration of nutrients, pesticides, and suspended sediments. Industrial activities can increase concentrations of metals and toxic chemicals, add suspended sediment, increase temperature, and lower dissolved oxygen in the water. Each of these effects can have a negative impact on the aquatic ecosystem and/or make water unsuitable for established or potential uses.
Q: Are agricultural pesticides considered a potential source of copper pollution for water?
A: Yes. According to a Fungicide Benefits Assessment Report by Gianessi and Puffer (Fungicide use in U.S. crop production. Resources for the Future, August, 1992), about 10 million pounds of copper was used in agricultural fungicides across the U.S. in 1991. Much of this copper is sprayed on plants and tends to accumulate in the immediate soil environment, making it susceptible to storm water runoff loss from agricultural operations. About 85 percent of the copper fungicides are used primarily on fruit, vegetable and nut crops in California and Florida.
Q: Are inert ingredients in pesticides toxic?
A: The term inert implies that a substance is non-toxic, but all inerts are toxic to some degree. The inert ingredients used in pesticide products must be tested to determine their toxicity. Only inert ingredients approved by EPA are allowed to be used in pesticide products. In addition, EPA encourages pesticide registrants to use the least toxic inerts in their products. In addition to testing the toxicity of the active ingredient, the toxicity of pesticide products, including the inert ingredients, must be determined.
Q: Do pets need to be protected from pesticide exposure?
A: Common pets like dogs and cats have similar susceptibility to pesticides as humans. However, they do not wear protective clothing. Pet habits, such as grooming, can also increase the risk of exposure. Pets such as birds, fish or amphibians, may be much more sensitive to certain pesticides. The risk from exposure to the same dose is greater for smaller animals.
Q: How am I exposed to pesticides?
A: Pesticides can be found, often in small amounts, almost anywhere worldwide. Where you live and your lifestyle largely determines the potential for exposure to pesticides. Most non-occupational exposure comes from food or home pesticide use. In addition to use in agriculture and forestry, pesticides are used in many public places, including office buildings, restaurants, schools, parks, golf courses, and along roads, railroads and power lines. People are not intentionally exposed to pesticides, except for public health reasons. Instructions on the pesticide label are designed to minimize exposure, both to workers and the general public.
Q: How do I dispose of old pesticides?
A: First, you need to decide what kinds of pesticides you have. Write down the names of the pesticides by brand name and active ingredients and estimate how old they are. Then you can call your county Extension office to help you identify the pesticides. If you have general use pesticides that you bought recently for home use and have kept stored properly, they may still be usable. Using up pesticides that are still good according to their label instructions is the best means of disposal. You can give such pesticides to a friend or neighbor to use up too. If you can't find anyone that wants them, you may be able to locate a household hazardous waste collection that will take them although such programs do not always take pesticides. If the pesticides are very old or are Restricted Use pesticides, they may be more toxic and difficult to dispose of. Old containers of pesticide may also be deteriorated and at risk of breakage. Some old pesticides may still be usable but many will not have good instructions for use. Restricted Use pesticides, which you need an applicators license to purchase, cannot be transferred to another person for use even if the other person has the appropriate license to use them. If a person has some usable restricted use pesticide that has not been cancelled or damaged, the original owner can use it up for any purpose that is on the label. If it cannot be used for any reason, it is very likely it will need disposal of as a hazardous waste. Many states are conducting special pesticide collection programs to allow both farmers and homeowners the opportunity to bring unused or un-wanted pesticides to a collection center for proper disposal. These programs are generally coordinated through local Extension offices.
Q: I don't use pesticides in my home garden. Why do farmers use them?
A: Home gardens are usually labor intensive. In addition to producing fruits, vegetables or ornamentals, people often garden for enjoyment and exercise. If a pest invades your garden patch, you can pick it off, pull it up, or do nothing and hope it will go away. Commercial agriculture is a for profit business. Chemical pest control plays a major role in modern agriculture, and has contributed to dramatic increases in crop yields over the past four decades for most field, fruit and vegetable crops. Pesticides have enabled some growers to produce some crops profitably in otherwise unsuitable locations, extend growing seasons, maintain product quality and extend shelf life.
Waste and Wastewater Management
Q: Are there special environmental and health considerations for land application of septage?
A: Yes, land application of septage comes under 40 CFR Part 503 regulations which define domestic septage as "either liquid or solid material removed from a septic tank, cesspool, portable toilet, Type III marine sanitation device, or similar treatment works that receive only domestic sewage" (USEPA, 1994). These regulations include methods of dealing with both environmental and health considerations to include potential pathogens, nutrients and contaminants such as some metals that are likely to be preferentially concentrated in septage solids. Under federal rules, septage can be applied to non-pubic contact sites, including agricultural fields, forest land and reclamation sites. To meet federal regulations to minimize attraction of vectors (such as flies and rats), land-applied septage must be treated by one of three means. It must be either 1) subsurface injected, 2) incorporated (surface applied and plowed under within six hours), or 3) alkali stabilized (pH raised to 12 or greater for 30 minutes prior to land-application). The federal regulations also include various restrictions on the crops that may be grown on the site and on access to the site by the public. The maximum application rate of domestic septage depends on the nitrogen content of the septage, the amount of nitrogen required by the crop that is grown and the planned yield of the crop grown on the site. Federal guidelines instruct septage applicators to use the following equation (USEPA, 1994): Annual Application Rate = Nitrogen Required for the Crop/0.0026.
Q: Do onsite/decentralized wastewater systems cause health or water quality problems?
A: Onsite/decentralized systems that are properly planned, designed, sited, installed, operated, and maintained can provide excellent wastewater treatment. However, systems that are sited in densities that exceed the treatment capacity of regional soils and systems that are poorly designed, installed, operated, or maintained can cause problems. The biggest documented problems involve contamination of surface waters and ground water with disease-causing pathogens and nitrates. Other problems include excessive nitrogen discharges to sensitive coastal waters and phosphorus pollution of inland surface waters, which increases algal growth and lowers dissolved oxygen levels. Contamination of important shellfish beds and swimming beaches by pathogens is also a concern in some coastal regions. EPA has developed guidelines to assist communities in establishing comprehensive management programs for onsite/decentralized wastewater systems to improve water quality and protect public health.
Q: How are nutrients removed at wastewater treatment plants?
A: Several methods can be used. Phosphate can be removed through addition of other chemicals, such as iron. Solid phosphate precipitates are formed and can be filtered from the water. The removal of ammonium nitrite and nitrate is a little more complicated. It takes purification processes that use both aerobic and anaerobic conversion. In the aerobic conversion stage there are two bacterial species involved. Nitrosomonas bacteria convert ammonia to nitrite and Nitrobacter bacteria convert nitrite to nitrate. This process is called nitrification. Although nitrate does not represent a direct health threat to most fish, high levels are still undesirable. Apart from encouraging abnormal extensive algal growth, it is now believed that high nitrate levels are implicated in some fish diseases. This means that the process cannot be stopped here. Anaerobic bacteria take over to convert nitrate to atmospheric nitrogen gas. This process only occurs in the absence of oxygen. The first stage is the reverse of the nitrification process, it converts nitrate back to nitrite. The second stage of denitrification converts nitrite to nitrogen gas (N2). This gas can be freely released into the atmosphere without causing environmental damage.
Water Conservation and Management
Q: How can water conservation be implemented?
A: There are many water-saving opportunities available to consumers, industry, and governments. Generally, three groups of actions are important - physical measures, economic measures, and social measures. Physical measures refer to alterations that can be made to water using equipment or processes. Domestic examples include the use of low-flow shower heads and water-conserving toilets, laundry facilities that recycle previously used water, and the implementation of universal water metering in communities. Industrial examples include the installation of water-recycling equipment, such as cooling towers, and process changes that lower water use. Economic measures refer to means of altering the ways in which users pay for the right to use water. Examples include revisions to municipal water rates to assure full cost recovery, water charges based on quantities used, and implementation of volume-based charges for self-supplied industries. Social measures refer to broad social policies and actions designed to lower water usage. Examples include revisions to plumbing codes, legal restrictions on water use during drought periods, and campaigns to inform the public about the importance of water.
Q: How much water can a small leak waste?
A: Water leaks cost money and waste huge volumes of water. Over 15 percent of the water in some municipal systems go unaccounted for, usually due to leaks outside of meters. This can be over a billion gallons per year on some large systems. A ¼-inch continuous water leak, at 60 psi, will waste 1,181,500 gallons in just 3 months and a 1/16-inch leak will waste 74,000 gallons during the same time. A single dripping faucet can waste 3 gallons per day...a total of over 1000 gallons per year. You pay the cost for the water wasted if it has passed through your meter. In reality everyone on a water system pays for the wasted water due the extra treatment costs to supply enough water to make up for that which is wasted.
Q: Is Xeriscape using native plants?
A: No; Xeriscape is gardening or landscaping by using many principles, such as grouping plants according to their water/light requirements, soil improvement, lawn minimization, etc. Native plants can be incorporated into the "Natural" zone of your Xeriscape. Xeriscaping can have many water, light and nutrient management benefits.
Q: What are the benefits of water conservation?
A: In addition to "stretching" available water supplies to meet increasing demands, water conservation has distinct economic advantages. For example, use of water-saving shower heads can not only save the homeowner the cost of the water itself but also save over $100 annually in water-heating costs. Furthermore, conservation retrofitting of an existing building could generate benefits ranging between 15 and 20 times the costs incurred. Finally, water conservation lessens the demands made on a vital natural resource, thereby contributing to the sustainability of our environment.
Q: What are the top ten practices to protect and conserve groundwater?
A: 1. Dispose of chemicals properly, do not store or use them near a well. 2. Take used motor oil to a recycling center. 3. Limit the amount of fertilizer used on plants, especially near a well. 4. Take short showers. 5. Shut water off while brushing teeth. 6. Run only full loads of dishes and laundry. 7. Check for leaky faucets and have them fixed. 8. Water plants only when necessary. 9. Keep a pitcher of drinking water in the refrigerator. 10. Get involved in water education.
Q: What is a rainwater harvesting system and what are its benefits?
A: A rainwater harvesting system is composed of a water collection system, a storage cistern and a water distribution system. The cisterns and any manholes or openings to them should be water tight with smooth interior surfaces. Cisterns see their greatest use in rural applications, especially with "green home" projects. In most cases the water collected is not used for drinking, but in some countries where natural rainfall is low, collected rainwater is often used for drinking. Modern benefits include reduced use of treated municipal water for landscape irrigation and other non potable needs, reduced need for a well, and a reduction in peak storm water volume.
Q: Do watersheds affect drinking water quantity and quality?
A: Most definitely. A watershed area is a unique and dynamic place and the conditions of a watershed, especially those areas nearest water, greatly affects the water quality. The best quality drinking water supplies from surface water sources usually come from relatively undisturbed watersheds or those managed to reduce pollution. Watersheds help maintain water supplies for drinking and other uses by retaining water from rainfall and snow melt and slowly providing it for stream flow, reservoirs and ground water recharge, thus conserving and preserving the volume of fresh water resources on the landscape.
Q: How can I be "watershed friendly"??
A: You can help protect your watershed and its water conditions by: a) Knowing where water goes when it leaves your property; b) Collecting and recycling used motor oil (Each year millions of gallons of used motor oil are poured down storm sewers or sent to landfills and some ends up in our water supplies.); c) Recycling newspapers, glass, plastic, and metal; d) Taking a soil test before determining the fertilizer mixture and application rate your lawn requires; e) Washing your automobiles on the lawn instead of the street or driveway to filter pollutants and reuse water; f) Knowing whether your home is hooked to a municipal sewer system or septic tank (If hooked to a septic system, have it checked regularly.); and g) Knowing the source of your drinking water and taking care to protect it.
Q: What do we mean when we talk about watersheds, river basins, catchment basins, and drainage basins?
A: Generally speaking, these four terms have similar meaning and are frequently used interchangeably. They refer simply to the total land area drained by a river and its tributaries. Originally, "watershed" denoted the imaginary line, or drainage divide, separating the waters flowing into different rivers or river basins, and is still often used in this context. Through common usage, it has also evolved to mean the area drained by a river system. "Drainage area" and "watershed" are more prevalent in North American practice, while "catchment" is customary in British and Australian water source communities. Each of the major river basins in the U.S. can be further divided into a hierarchy of progressively smaller basins or watersheds down to areas that drain to individual lakes and smaller and smaller drainage channels.
Q: What features make a watershed unique?
A: The most unique features of a watershed are its boundary, terrain, soil type and land use. The geographic boundary of a watershed determines its physical size. This boundary is usually a ridge or high area from which water either drains towards or away from a particular watershed. How flat or how steep (terrain) the land is impacts how fast the water drains throughout and from a watershed. The faster the drainage, the greater for potential flooding and potential erosion and sediment discharge from the watershed. Sandy soil allows the ground to soak up water faster, reducing runoff. Clay soils do not allow as much water infiltration, leading to greater runoff. Soils are classified into four hydrologic groups based on runoff potential. Land use, especially that nearest the water, can heavily impact a watershed. Runoff quality and quantity varies significantly over time, depending on whether land use next to a water flow channel is a filter, a buffer strip, wildlife habitat, wetlands, industry, urban/suburban or agriculture.
Q: What is a watershed?
A: A watershed is an area of land, that drains into a river, lake, stream, pond, or other body of water. It includes the waterway itself and the entire land area that drains into it. For example, the watershed for a lake includes any streams emptying into the lake and the land area that drains into those streams. A watershed can be small, like a backyard puddle, or large, such as the Mississippi River drainage basin.
Q: Why is a watershed important?
A: We all live in a watershed and we all rely on this water and other natural resources to exist. The type of land use--agricultural, urban, suburban--and its associated activities have a direct impact on the water quality of the watershed. When it rains or when snow melts, the water runs downhill into the waters carrying the effects of human activities into the waters of the watershed. What you and others do on the land impacts the quality and quantity of our water. A healthy watershed is necessary for a healthy environment and economy. Many watersheds provide a community with water for drinking, irrigation, industry, and for recreation. Wildlife also depend on a healthy watershed for their food and shelter. We are all responsible for preserving and protecting our watersheds.