An associated Press investigation revealed that traces of pharmaceutical drugs are being found in treated drinking water in countries worldwide.

The fact is crystal clear drinking water can contain numerous contaminants that are odourless, colourless and completely invisible to the human eye yet are potentially hazardous to human health.

In some countries, people drink water straight from the tap. However in most developed or developing countries, water is treated before being piped to consumers. Although very few people drink water straight from the tap, it is common to swallow a little tap water each time we brush our teeth or during a shower. Since we don't get sick, we can conclude that tap water is "safe" or to use a more technical term, "potable."

The next question to ask is: Does "safe" tap water pose a health risk if we drink it over a long period of time? Thus, we need to consider that "safe" in the short term does not always equate to "healthy" in the long term.

Adding to the problem, recent investigations have shown that pharmaceutical drugs bypass modern wastewater treatment processes and are, finding their way into drinking water world wide.

There may have no immediate health effects from consuming minute's traces of drugs in the water but there will be a potential harmful cumulative effect from persistent exposure to random combination of low level of drugs. Unlike bacteria or even chemical based pollutants frequently found in water, pharmaceuticals are purposely designed to have specific effects on the human body in relatively small doses.

These pharmaceuticals enter our water systems and underground water sources through unabsorbed un-metabolised medications that are flushed out of our bodies and into the toilet. In addition, millions of kilograms of expired or over-prescribed medications are discarded into toilets and dumpsites.

To date, there are no mandated testing requirements for the presence of pharmaceutical drugs in drinking water. However, studies have shown that pharmaceuticals in water are causing the feminisation of male fish. Scientists were also able to link drug-dumping to virulent antibiotic-resistant germs and genetic mutations that may promote cancer.

The latest studies show that drugs in water are linked to declining male fertility and tests demonstrate that human cells fail to grow normally in the laboratory when exposed to trace concentrations of certain drugs. In the worst-case scenario, can you imagine your child drinking some stranger's heart medication, or your son drinking traces of sex hormones on a daily basis? It's an alarming thought isn't it? But, that is exactly what is happening today!

The magnitude of this problem has led to many human health impact studies.

Conventional wastewater and water treatment systems are simply not capable of eliminating these traces of dangerous contaminants. There is simply no sewage treatment system engineered to remove pharmaceuticals in water.

In municipalities across the world, a powerful disinfection compound known as chlorine is used to kill bacteria and viruses. However, chlorine can actually make some of the pharmaceutical contaminants even more dangerous. Chlorine also reacts with organic matter, which naturally occurs in reservoirs, rivers and streams used as the source of drinking water. This reaction creates disinfection by-products (DBPs), which are carcinogenic, meaning they are cancer causing. Studies have shown that people who drink chlorinated water have a higher risk of certain types of cancer than people who don't drink chlorinated water.

Bottled water is not much better. Lab tests on 10 leading brands of bottled water in the US detected 38 chemicals, including bacteria, the pain reliever acetaminophen, fertiliser, plastic-making chemicals and the radioactive strontium.

People today are increasingly becoming aware of the importance of drinking just pure water. But can water totally devoid of minerals be "too pure" for health? Do we need minerals in our drinking water? Even though there are differing opinions, I am personally sure that the answer is no!

Firstly, most minerals in water are inorganic since the minerals in stones and rocks are dissolved by water as it seeps through the ground. These cannot be easily assimilated or used by our body. Otherwise, we might as well chew rocks to get our daily calcium requirement!

Secondly, there is no home water treatment system in the world that can differentiate between so-called "good" minerals such as calcium or magnesium and "bad" minerals such as nitrates or arsenic. If you consider that nature's way of providing the entire Earth with water (through rain or snow) contains no minerals, it stands to reason that our drinking water should be the same.

There are many types of water systems in the market. Most are water treatment systems, which basically remove some particles and maybe smell and colour in water. However, a properly designed purification system does much more.

Although affordability is a key factor, health is much more valuable in the long run. The function of a water system is to clean and improve the water. So, choose one that is able to rid contaminants besides being able to improve the water's taste and colour.

One of the best ways to produce high purity water is by using a process called Reverse Osmosis (RO). RO is used by major multinational corporations; especially those involved in the food and beverage industry, bottled water production and desalination plants worldwide (which converts seawater into drinking water).

In RO, water is forced (by pressure) through a special membrane to purify it at the molecular level. The incredibly small pores of the membrane allow water molecules to pass through while rejecting virtually all other contaminants. In very high quality Reverse Osmosis systems, the effective porosity of the RO membrane is 0.0001 microns in diameter - that's about 500,000 times smaller than the diameter of your hair!

According to the UN Global Outlook Report of 2007, over one-third of all humans worldwide will suffer from the lack of safe drinking water by 2025. It is very clear to many that water will become the next "oil." Therefore it makes sense for us to protect ourselves, and improve our health by investing in a good water purification system.

1) The technology

2) Contaminants it can remove

3) Ask about after-sales service

4) Company background: how many years the company has been in the business

5) Find out if the company has been accredited by an independent body