Who is Responsible Drinking Water Quality?

The Safe Drinking Water Act gives the Environmental Protection Agency (EPA) the responsibility The Safe Drinking Water Act gives the Environmental Protection Agency (EPA) the responsibility for setting national drinking water standards that protect the health of the 250 million people who get their water from public water systems. Other people get their water from private wells which are not subject to Federal Regulations. Since 1974, EPA has set national safety standards for over 80 contaminants that may occur in drinking water.

While EPA and state governments set and enforce standards, local governments and private water suppliers have direct responsibility for the quality of the water that flows to your tap. Water systems test and treat their water, maintain the distribution systems that deliver water to consumers, and report on their water quality to the state. States and EPA provide technical assistance to water suppliers and can take legal action against systems that fail to provide water that meets state and EPA standards.

For more information

• Read Water on Tap: What You Need To Know
• Find out what's going on in your state. Find its drinking water web site through EPA's local drinking water information web site . This site will also help you find information about your drinking water supplier.
• EPA's rules don't apply to water from private wells, but EPA does have some recommendations for people who get water from private wells.
• To learn how EPA sets limits on drinking water contaminants, read Setting Standards for Safe Drinking Water .
• Read the complete Safe Drinking Water Act or a summary of the 1996 Amendments to the Act..
• Each state writes an annual report on its systems' compliance with drinking water rules. EPA compiles and analyzes these reports in its Compliance Report.
  

The Water Cycle Info

Introduction

As seen from space, one of the most unique features of our home planet is the water, in both liquid and frozen forms, that covers approximately 75% of the Earth's surface. Believed to have initially arrived on the surface through the emissions of ancient volcanoes, geologic evidence suggests that large amounts of water have likely flowed on Earth for the past 3.8 billion years, most of its existence. As a vital substance that sets the Earth apart from the rest of the planets in our solar system, water is a necessary ingredient for the development and nourishment of life.

Water, Water, Everywhere

Water is everywhere on Earth and is the only known substance that can naturally exist as a gas, liquid, and solid within the relatively small range of air temperatures and pressures found at the Earth's surface. In all, the Earth's water content is about 1.39 billion cubic kilometers (331 million cubic miles) and the vast bulk of it, about 96.5%, is in the global oceans. Approximately 1.7% is stored in the polar icecaps, glaciers, and permanent snow, and another 1.7% is stored in groundwater, lakes, rivers, streams, and soil. Finally, a thousandth of 1% exists as water vapor in the Earth's atmosphere.

One estimate of global water distribution:

	Volume (1000 km3)	Percent of Total Water	Percent of Fresh Water
Oceans, Seas, & Bays	1,338,000	96.5
Ice caps, Glaciers, & Permanent Snow	24,064	1.74	68.7
Groundwater	23,400	1.7	-
Fresh	(10,530)	(0.76)	30.1
Saline	(12,870)	(0.94)	-
Soil Moisture	16.5	0.001	0.05
Ground Ice & Permafrost	300	0.022	0.86
Lakes	176.4	0.013
Fresh	(91.0)	(0.007)	.26
Saline	(85.4)	(0.006)	-
Atmosphere	12.9	0.001	0.04
Swamp Water	11.47	0.0008	0.03
Rivers	2.12	0.0002	0.006
Biological Water	1.12	0.0001	0.003
Total	1,385,984	100.0

Source: Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp.817-823.

Estimates of groundwater are particularly difficult and vary widely amongst sources, with the value in this table being near the high end of the range. Using the values in this table, groundwater constitutes approximately 30% of fresh water, whereas ice (including ice caps, glaciers, permanent snow, ground ice, and permafrost) constitute approximately 70% of fresh water. With other estimates, groundwater is sometimes listed as 22% and ice as 78% of fresh water.

Solar Water Heating System

Like solar collectors, solar water heaters can be either passive or active. Passive systems have no moving parts, no external energy source except the sun, and rely on the basic principle of physics that hot water rises and cold water falls. Active systems utilize a mechanical circulating pump and some type of temperature control.


A simple passive solar water heater consists of a water tank that has been painted black and placed in a well-insulated box that has glass or plastic on one side. The sun’s rays penetrate the glass and heat the tank. This type of system is often called a “bread box” or batch heater. It allows cold water to flow in at the bottom and hot water to flow out from the top. The system operates on water pressure from the water supply. Water from the system is then transferred to a conventional gas or electric water heater. A thermostat on the water heater determines whether the water is hot enough to be used. If it is not, the conventional water heater adds the required heat.