http://www.lowes.com/pd_192585-82589-WGM00023_0__?productId=3083093
Pea gravel from lowes

http://www.aquapurefilters.com/contaminants/106/ammonia.html
It is usually in fertilizer, and has a lot of nitrogen. it gets into water through runoff, and easily is absorbed. It is also a danger with copper, and can be removed with chlorinization. It forms chlorimine, which ends up as chlorine residue. It can also be removed with something called degasification.

Common water-borne pathogens

Diarrhea- caused by many different pathogens, bacteria, viruses, protozoans. It causes loss of water and electrolytes in the body, leading to dehydration and/or death.

Cholera- bacterial infection, causes acute diarrhea leading to dehydration and death.

Guinea worm disease- caused by swallowing the larvae of the worm, and leads to the adults in the skin, reaching up to a meter long, and leaving debilitating ulcers.

Malaria- spread by mosquitoes, but can reduce the mosquito pop. by eliminating standing water (open tanks, bad drainage) with good filtration.

Trachoma- and eye infection (bacterial) caused by bad water supplies for bathing, with better filtration and pipes people can eliminate this infection.

Typhoid- bacterial infection caused by bad food/water, characterized by headaches, nausea and loss of appetite.

Fluorosis- a disease heavily effecting bones, caused by high amounts of fluoride in natural groundwater.

This type of info is needed so that we know what types of things we would possibly need to filter.

Diarrhoea Diarrhoea is caused by a variety of micro-organisms including viruses, bacteria and protozoans. Diarrhoea causes a person to lose both water and electrolytes,, which leads to dehydration and, in some cases, to death. About 4 billion cases of diarrhoea per year cause 1.8 million deaths, over 90 per cent of them (1.6 million) among children under five.

Table 5