How Do Water Treatment Plants Work?

Clean and safe drinking water is something that most people in the United States have been taking for granted. Treated water is used every day, and it can be used by turning on a faucet, taking a shower, and watering the lawn. Have you ever wondered how that water is cleaned and distributed to your house? That’s where water treatment plants come in.

Water treatment plants play an important role in ensuring that the water we use is safe to consume, cook with, or use in other day-to-day activities. In this guide we will look at how water treatment plants are effective beginning at the source all the way to the tap.

Why Is Water Treatment Necessary?

Why should our water be treated? Before we get into the process, we should see why there is a need to treat water in the first place.

Removing Contaminants

Natural sources of water like rivers, lakes, and ground water may contain:

· Bacteria and viruses

· Dirt and sediment

· Chemicals and pollutants

· Heavy metals (like lead or mercury)

Drinking impure water can lead to contracting diseases that could lead to diarrhoea, cholera, or chronic illness as a result of chemical poisoning.

Meeting Federal Standards

In the United States, the Environmental Protection Agency (EPA) has developed very strict standards of water quality. Water treatment plants ensure that water is safe before it is supplied into our homes.

Where Does the Water Come From?

The journey begins at the source. This could be:

Surface water: lakes, rivers, or reservoirs

Groundwater: water pumped from underground aquifers

Water treatment plants can harness from either of the sources or both depending on availability and location.

Step-by-Step: How Water Treatment Plants Work

Let’s break down the process into key steps. In the United States, the structure of most municipal water treatment plants is similar, but other kinds of technologies may be employed based on the local water source and regulations.

Step 1: Coagulation and Flocculation

This is to eliminate dirt and particles.

· Coagulation: The water is treated with chemicals (e.g., alum or ferric sulfate). These cause tiny particles to stick together.

· Flocculation: This is the process of gentle mixing to form larger aggregates of particles termed as flocs.

These flocs are denser and can be removed more easily out of water.

Step 2: Sedimentation

Once the flocs are formed, they are conveyed to a sedimentation basin.

· In this instance, gravity will cause heavy flocs to settle.

· The clear water is separated on the top and sent to the next stage.

Step 3: Filtration

The filtered water is then passed through sand, gravel, or charcoal filters.

· These filters remove any other particles, dirt, and some bacteria.

· In more advanced plants, membrane filtration or activated carbon filters may be employed to remove chemicals and contaminants as well.

Filtration is essential for improving water clarity and taste.

Step 4: Disinfection

Even after filtration, water may still contain harmful microorganisms. To kill these, the water is disinfected.

Common disinfectants include:

· Chlorine: Most widely used in the U.S.

· Chloramine: A combination of chlorine and ammonia

· Ozone or UV light: Ozone or UV light are the latest systems to be used

The water is also disinfected so that it is microbiologically safe prior to being distributed.

Step 5: Storage and Distribution

After disinfection, the water is stored in large tanks or reservoirs.

From there:

· It is passed through a network of pumps and underground pipes.

· Water can be distributed on demand to schools, homes, and businesses, among other places.

Water pressure is maintained by pumps or through the force of gravity depending on how the distribution system is designed.

Optional Steps in Some Water Plants

pH Adjustment

There may be some water sources that are too acidic or alkaline. Treatment plants may introduce chemicals, like lime, to alter the pH of the water so that it is safer to use in plumbing and less destructive in regards to corrosion.

Fluoridation

Fluoride is used to prevent tooth decay in most communities in the U.S.  Fluoridation is usually determined by local government.

What Happens to Waste from Water Treatment?

The treatment of water does not only produce clean water, but also, waste like:

· Sludge (from sedimentation tanks)

· Backwash water (used to clean filters)

This waste is treated in a different manner in order to prevent environmental degradation.

It may be sent to:

· A wastewater treatment plant

· A landfill

· A sludge treatment facility

Ensuring Water Quality: Testing and Monitoring

Water treatment plants are required to conduct frequent water quality tests in the process of water treatment.

This includes:

· Checking for bacteria

· Monitoring chlorine levels

· Testing for harmful chemicals (like lead, nitrates, or pesticides)

The U.S. conducts annual reporting of the quality of water delivered by the public water systems in the form of a Consumer Confidence Report (CCR).

Common Technologies in Modern Plants

Modern water treatment plants may use advanced technologies, including:

· Reverse Osmosis: Removes dissolved salts and contaminants

· UV Disinfection: Kills bacteria without chemicals

· Advanced Oxidation Processes (AOPs): Removes chemical pollutants

These are typically used where the water source is so polluted or in drought hit areas where reuse of water is essential.

What You Can Do at Home

Your water treatment plant can do a phenomenal job.

There are other precautions you can take to ensure that water quality at home is good too:

· Use a certified water filter (if desired)

· Regularly clean faucet aerators

· Test your tap water especially when your pipes at home are old

· Stay informed by reading your local CCR report