Mech/Elec ALS Lesson Seven - Water Supply And Drainage Systems: Supply - Hardness & Carcinogens & Disease (Oh My!)

Topics:
Supply-Hardness
Supply-Carcinogens
Supply-Disease

Hardness
Water seeping into the ground dissolves minerals from the ground
Commonly Limestone and/or Calcium and/or Magnesium.
This creates hard water.

Usually not harmfull to humans but harmfull to plumbing.
These minerals leave deposits on pipe walls eventually clogging the flow.

Also a problem for heat exchangers like hot water tanks and hydronic systems.
Deposits choke the flow or insulate the pipe so heat is not transferred.
A metal Anode can be inserted into the tank to collect the deposits instead of on the walls.

Hardness interferes with cleaning in the way soap and detergents react with the water.
ions already dissolved in the water from the minerals can prevent additional dirt from being dissolved(cleaned).
The minerals can coagulate with the soap to form a soft paste in the plumbing

Water softening is the process used to reduce the amount of dissolved minerals
Either remove the mineral ions or combine them with something that will not solidify when heated.
Zeolite or ion exchange process
Two tank process, first contains Zeolite mineral, second contains salt crystals


Carcinogens
These are cancer causing agents that must be tested for and avoided.
Largely but not limited to PCB's (Poly chlorinated biphenyls), DDT and other insecticides and asbestos fibers.


Disease
Bacteria and viruses
Usually comes from improper disposal of human and animal waste or other organic materials that decay and are a source and a breeding ground for disease-causing bacteria and viruses.
Traditional treatment = settling out contaminants
Adding alum causes coagulation and sediment to settle out.
Chlorine can be added to kill or reduce bacteria. At 0.5 ppm (parts per million), Over 1 ppm, you get a distinct chlorine taste.
Fluorine can be added to improve rooth decay resistance.
Oxygen added if enough is not already present in the water, by passing through a spray or waterfall. Oxygen makes it more fit for consumption but also increases rate of rusting in iron based (ferrous) fittings.