The future of real-time purification for developing countries

Solving the global water contamination crisis

Nyla Pirani
11 min readFeb 5, 2021


Every year approximately 3.5M+ people die from water-related diseases that are completely preventable. This is equivalent to a jumbo jet crashing every hour.

A few months ago when I heard that number, I was speechless. What really got to me was that around 2.2M of those people are children!

You and I have probably never had to worry about death simply from drinking water, but millions of children around the world are terrified of this.

We can all agree that access to clean water is an essential human right and it didn’t make sense to me that these millions of people were deprived of that. So, I decided to look into the problem further.

The Water Crisis

When I was looking at this problem, I broke it down into two main aspects: water access and water cleanliness.

Water access is a huge infrastructure problem that links to open defecation, high demand but low supply, governmental corruption, lack of adequate technology and more.

After having a general understanding of the access portion I decided to focus on the cleanliness of the water. The reason behind this was that, (best case scenario) solving open defection, increasing supply etc. wasn’t going to make the water clean which was my initial main goal.

So, I spent the last month diving deeper into the cleanliness of the water.

For this portion, the information will mainly be focused on Uganda unless stated otherwise but can be applied to the majority of third world countries.

The Water Contamination Crisis

19% of the Ugandan population relies on unimproved or surface water for their daily needs. This means that over 8 million people are drinking from sources like streams, ponds, unprotected hand-dug wells, and more.

What I wanted to understand was the impact of drinking from unimproved or surface water sources. The way I measured this was by looking at the highest water borne diseases and their death rates.

An estimated 11–21 million cases of typhoid fever and 200,000 deaths occur worldwide each year (this isn’t specific to Uganda).

In 2016, 132,121 cholera cases and 2420 deaths were reported to WHO worldwide. Overall, 54% of cases were reported from Africa (this refers to all of Africa).

Pneumonia is a leading cause of death among children under five years of age (Uganda) and approximately 23,000 Ugandans (including 19,700 children under 5) die each year from diarrhea (nearly 90% of is directly attributed to poor water, sanitation and hygiene — (WASH)). This is directly correlated with E Coli.

An E Coli breakout in Uganda that killed thousands of people

As you can see the number of people dying from these (preventable) waterborne diseases is insane.

Once I understood the scope of this problem I wanted to clearly breakdown the main contamination points of the water and their root causes. It really came down to two main things:

  1. Anthropogenic activities (mining and smelting operations, industrial production and use, and domestic and agricultural use of metals)
  2. Open defecation

Here’s a chart that clearly breaks down the root causes:


  • Heavy metal contaminants come from anthropogenic activities. For example, acid rain will break down soils and release heavy metals into the water. (Acid rain is usually experienced in the month of August after the mid-year dry season in Uganda.)
  • E Coli is found in animal feces (mainly cattle) and animals in Uganda are defecating in the open which is contaminating water sources.
  • Cholera is passed along through water sources that are contaminated with the feces of an infected person. Over 3 million people in rural Uganda practice open defecation.
  • Typhoid is commonly passed through using toilets that have contaminated feces and touching your face/mouth before thoroughly washing your hands. This means drinking water from water sources contaminated with infected feces (Over 3 million people in rural Uganda practice open defecation) .will expose people to Typhoid.

Existing Solutions

After having a clear, validated breakdown for the water contaminates I wanted to look into existing solutions to understand how people were currently cleaning the water.

I found three methods of how people currently clean water: boiling, solar disinfection and biosand filters.


About 60% of people in Uganda will boil their drinking water. To boil the water, the communities will collect and burn firewood under the water.

However, there are a few struggles along with some limitations to this method.

The first struggle is the effect it has on women and children. They typically spend hours every day collecting firewood and water which means they don’t have the ability to go to school or go to work and earn money.

The second struggle I found was the dwindling forests and the fact that it produces CO2 emissions. This creates a polluted environment which leads to a whole other set of problems. (Learn more about the effects of air pollution on humans).

The two limitations I found were around education and cost.

The majority of people boiling the water aren’t doing it correctly. A study done on 26 women revealed that 4 out of the 26 women stopped boiling their water once vapours appeared; the average temperature for this was 74.6°C. The remaining 22 women brought the water to a surface boil (100°C). Only two women continued to boil water once it reached a surface boil for 3 and 5 minutes each. In another study that was done, only 2 out of 1760 women boiled the water correctly.

The water can also be recontaminated if not handled properly.

In terms of the cost limitation, an average of $200 is spent every two years per family on the fuel needed to boil water. For families that need to live on $1 or less a day, this is incredibly expensive.

Solar Disinfection

The second method I found that people use to disinfect water is called solar disinfection. In developing countries, roughly 5 million people use it daily.

People will place bottles of water into the sunlight and will leave it there for hours. The UV radiation and solar light will kill the bacteria over time. It can take anywhere from 6–48 hours depending on the weather conditions.

The bonuses to this method are that it’s cheap, convenient and simple. A lot of kids will leave their water outside well they attend school and get it before they leave.

But, it does have its limitations.

The first one is that the water needs to be consumed within 24 hours otherwise there is a possibility of it being recontaminated.

The second one is that it needs constant sunlight but there is no real way to tell how long it needs to be in the sun. You have no way to tell when it’s actually decontaminated. For example, it takes 3 hours to eliminate somatic phages but other viruses can take 12.5 hours (or longer) to be fully eliminated.

The last large limitation I found was that you can usually only put 2L of water per bottle when you use this method.

As you can tell these methods aren't very effective and it becomes incredibly hard to ensure that the water was disinfected correctly / fully and that it doesn’t get reinfected.

Biosand Filters

On average a single biofilter filter costs a total of $70USD to construct and install for about 10–15 people.

These filters can last up to 30 years if properly maintained and the way you clean them is very easy.

This means the cost isn’t a huge limitation because it serves 10–15 people and is incredibly sustainable.

Studies have shown a biosand filter can remove more than 90% of bacteria and 100% of parasites. They can also remove 3 main metals — chromium, cadmium, and iron.

A Biosand filter is made up of a container(either plastic or concrete) and is about the size of an office water cooler. It has an inset plastic pipe and is filled with layers of sand and gravel. Dirty water is poured into the top of the Biosand filter, where a diffuser plate evenly distributes the water over the sand bed layer. The water travels down through the sand bed, passes through multiple layers of gravel, and collects in the plastic pipe at the bottom of the filter. The clean water then exits through the plastic piping for a family to collect in clean containers.

Diffrent types if Biosand filters

The combination of biological degradation and mechanical filtration processes is what's used to eliminate contaminants and disease. The organic material within the dirty water is trapped at the surface of the sand bed, forming a biological layer, which is actively able to remove pathogens and contaminants.

All the water produced with the filter is tasteless, clear in colour, odourless and safe for drinking.

Currently, nearly 500,000 people worldwide use Biosand filters.

Case Study- Posoltega, Nicaragua.

There was a case study done on the implementation of Biosand filters in Posoltega, Nicaragua.

The average filtration efficiency was found to be 98% for total coliforms, 96% for E. coli and 88% for turbidity.

The filtered water and the stored post-filtered water didn’t meet the WHO guidelines for safe drinking water due to the presence of E. coli. Also identified were improper maintenance practices and unsafe storage of post-filtered water.


One disadvantage to Biosand filters is that they’re incredibly heavy. It takes at least two people to lift even an empty filter with no sand in it.

The second limitation (which we saw in the case study), is that people aren’t educated on the proper methods to store the water after it’s filtered nor is there an effective way to store it to ensure it doesn’t get recontaminated.

The future of real-time purification

These methods are generally applicable to any developing countries around the world. Looking at the weather conditions, way of life, etc. at any specific country could tell you whether this solution would be effective.

In the last decade, we’ve had tons of technological and scientific advancements. This means that we also have a bunch of new ways to get access to clean water.

A lot of these methods aren’t cost-effective yet, so it would be a struggle to implement them in developing countries, but as we progress they will become more cost-effective and easily implementable.

The criteria I looked at for these water systems was:

  1. Cost — people living in developing countries don’t have hundreds of dollars sitting around.
  2. Sustainability — I wanted to ensure that the water source wasn't something that constantly had to be replaced because that’s a huge inconvenience.
  3. What the system filtered out — if the method I was exploring didn’t filter out everything in the water the implementation wouldn’t have been very useful.

After I understood those I looked into the functionality and limitations of each device to get a grasp of what we need to improve.

Dewgood — Harvesting Water From Air

When water vapour in the air comes into contact with something cold its molecules slow down and get closer together. When that happens, the water vapour turns into liquid water droplets. The DG-10 is the Dewgood product that is able to speed up that process by using electricity.

It has a built-in 6 stage filtration system, including a UV and carbon filter, so the water that comes straight from the machine is basically distilled.

This machine uses about 500–800 watts which is basically the equivalent of a desktop computer and is capable of producing 10 gallons (37 litres) of freshwater every day.

The DG-10 costs about $1,499 USD but they aren’t currently selling the product and it’s only available for preorder.

Depending on how much water you are generating the air and 6 stage water filters will need to be changed every 6–12 months.


The first clear limitation is the cost of the product. The second limitation is the amount of electricity it takes to power. Only about 42.65% of the Uganda population has access to electricity so this is a huge barrier to entry.

Zero mass water — Creating Drinking Water by Combining Sunlight and Air

Zero mass water is a company with a product called SOURCE which is a solar-powered and infrastructure-free drinking water solution.

What the product looks like

How it works:

  1. Solar energy powers the panel completely off-grid.
  2. Fans draw in ambient air and push it through a hygroscopic (a water-absorbing material) that traps water vapour from the air.
  3. The water vapour is extracted and passively condenses into a liquid that is collected in the reservoir.
  4. Minerals are added to the water to make it distilled.

It can produce 12 standard bottles, for less than $0.15 per bottle every day.

There is also a 30-litre (60 bottles worth) reservoir that can store water safely for about a week.

SOURCE is fairly low maintenance. It requires the air filter and polishing cartridge to be changed once annually, and the mineral cartridge once every five years but they have a 15-year overall lifespan.

A standard SOURCE array is 2 Hydropanels, at an estimated project cost between $5,500 and $6,500.


The biggest limitation here is the cost. People in developing countries have to live on almost nothing which means they can’t afford to pay for a device like this.

Gravity Water — Using Rain Water

Rainwater isn’t commonly at risk of pollutants until it reaches the ground where contamination occurs and WHO considers rain as an “Improved Drinking Water Source”. Gravity Water is leveraging this to provide people access to clean drinking water.

Rainwater harvesting set up for one of Gravity Water’s systems at a public school in Kathmandu, Nepal

Essentially what these systems do is capture rainwater and use gravity to provide pressure for filtration. The means people don’t need to rely on electricity that they don’t actually have access to.

Gravity Water systems are built completely with locally sourced materials that are commonly found in developing countries (water tanks, basic filters, plumbing materials, cement, and metal) which means that local families have a general exposure to the materials so it’s not complex for the communities to build or maintain. It also allows for them to support local businesses.

The development of the systems is fairly basic and the local communities are involved in all the development processes.


The biggest limitation I see here is the dependence on it raining. The vast majority of people who don’t have access to safe drinking water around the world live in the Tropics and Sub-tropics and in many tropical and subtropical regions, rainfall varies much more than temperature does so it’s fairly unpredictable. But other than that it’s a very promising solution.

At the end of the day when you look at all this information, the thing that matters the most to me is that there are still people dying. We have access to all these technologies and methods of collecting water, but we still have a long way to go.

The major point we need to target is the cost of all these products. They’re all effective in practice, but these people don’t have access to the money they need to implement it. If we can find ways to fund these projects or lower the cost altogether, the water contamination crisis won’t stand a chance.

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— Nyla Pirani