Stormwater Run-off Effect On Drinking Water

Having clean drinking water is a necessity for every person in the world. We need water to survive, and it must be up to the proper standards to drink it. Water quality can be affected by numerous things such as climate, pollution, and most importantly, storm run-off. Storm water run-off can contaminate a local water source to where it cannot be filtered well enough, making it undrinkable. Storm water run-off is a growing problem for many areas. Run-off occurs when water flows off of surfaces such as roofs, pavement, hills, and other areas.

As it flows into a water source, it collects chemicals such as herbicides, pesticides, and toxic metals. It also collects crap such as debris, mud, oil, and even actual feces. But the good news is, people have noticed this problem and have begun creating ways to help reduce it.

A huge development that has been adopted throughout many cities are permeable pavements. VTT Technical Research Centre of Finland has developed these pavements to reduce this problem in urban areas.

The VTT explains that, “The permeable pavement consists of a surfacing layer and sub-surfacing materials with high porosity that can retain water.” (VTT, 2) This is a huge step in helping this problem because storm water run-off won’t be carelessly flooding areas and picking up all of the nasty chemicals. Another huge discovery was made by the University of California, Berkeley engineers. They discovered a new way to remove contaminants from storm water. They use a mineral-coated sand that destroys pollutants.

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They have discovered that the sand could help purify storm water in underground aquifers. It would create a safe and local reservoir of drinking water.

Think of it like a giant rain barrel that stores this water underground during times of heavy rainfall. Although things like this already exist like rain gardens, it is on a much bigger scale and could be way more effective. It turns surface run-off into drinking water. To create this coated sand, they mixed plain sand with two forms of manganese that react to make manganese oxide. It binds to organic chemicals such as herbicides and pesticides. It breaks them down into small particles which is a lot less toxic. They tested the sand by putting simulated storm water through it. The sand initially removed all of the chemicals, but lost its effectiveness over time. They found out that it could in fact be “recharged” by putting a solution through the sand containing a low amount of chlorine. This would restore the manganese oxides reactivity. This would be way more efficient than digging up and replacing the sand.

The EPA has a citizen handbook called, “Urban Stormwater Runoff”. Throughout the handbook, the issues that run-off causes are addressed. It also explains control plans for this problem. State and local governments and area wide planning agencies are responsible for developing these control plans. A lot goes into these plans such as water quality goals and standards, monitoring water quality, surface water characteristics, and much more. They also have to take environmental factors into consideration like soils, slopes, surface cover, climate, pollutant types, and amounts. The handbook even explains how construction is the main source of most run-off pollution. Sediment is the most common pollutant, but other substances such as asphalt, paint, and cleaning solvents also contribute. The solution is to just be aware of the problem and take steps to help prevent it such as some of the ideas stated earlier in this paper.

Stormwater run-off can get so bad sometimes, it can contaminate a local water source making it hard to filter it into drinking water. When it gets this bad, the water treatment plant has trouble keeping up. This is how the treatment plant works. Water starts off in a local body of water and is sent through the water treatment plant. Majority of them start out with a process called coagulation where solids are removed by sedimentation. During coagulation a chemical is added called alum which produces positive charges to neutralize the negative charges of the particles. This makes the particles stick together in larger clumps and makes it way easier to remove. The next step is flocculation; this is where the water flows into a tank with mixing paddles. Since the particles now have a neutral charge, they can stick together. The water flows through the slow moving mixing paddles to bring the particles together to form larger particles called flocs.

If the mixing is done too fast the flocs will break apart into smaller particles which are difficult to remove. Next the water flows into a sedimentation basin where gravity makes the floc settle at the bottom of the tank. This makes sludge, which is pumped out. The clarified water moves to the filtration step where the smaller particles can be removed. When the water flows to the filtration box, the water falls down through a layer of sand which traps the particles and a layer of gravel to keep the sand from getting out. The underdrain of the tank collects all of the filtered water and sends it to the disinfection stage. They add some chlorine into the water to destroy the rest of the pathogens. The finalized water has to meet a required set of guidelines set by the EPA. This includes proper turbidity, and other chemical tests. The water plant can then distribute the clean water to communities, or pump the water into reservoirs called water storage tanks.

A couple of months ago, Austin, Texas had a run-off dilemma. With very heavy rainfall, a high level of debris, silt, and mud required additional filtration that slows down the process of treating water. “Today, we are now asking you to not drink from the sink.” (Anchondo 3) The city of Austin had to issue a mandatory boil notice to all of the residents. This means that before you drink the water you need to boil it for at least three minutes. This cleans and filters the water. This was mandatory before you drink it, cook with it, and even to brush your teeth. Showering and doing laundry were presumed safe. This affected hospitals, schools, and food services all around Austin. This actually happens quite frequently around the world and is not always caused by storm water run-off. But most of the situations are because of run-off. Thankfully there is a federal law that protects public drinking water throughout the nation. This is called the “Safe Drinking Water Act.”

The EPA sets standards for the quality of our drinking water and has multiple technical and financial programs to ensure our safety. The agency sets regulatory limits for the amounts of certain contaminants in our water. With the knowledge that we have about filtering water and all of the people concerned about this problem, I am confident that we can fix it. People at universities and other research facilities are coming up with new ways to filter water and help manage all of this run-off. With all of these new ideas, we can put them into place with proper funding and planning. We could create a world where run-off wouldn’t contaminate water sources and wouldn’t cause problems with water treatment plants. People need safe drinking water to survive, so keeping water clean is crucial.