• Written by Arthur Heijstek
    9 August 2017

Over the last couple of years, we’ve been testing and improving the water quality tests that Akvo Caddisfly (our simple, low cost, open source, smartphone-based water quality testing system connected to an online data platform) performs, as well as adding new parameters to test for different types of contaminants. During this process, we found that moving from high fidelity prototypes towards certified and scalable hardware products is a challenge. After some deep thought we came to the conclusion that the best way to rapidly achieve our goal of a truly scalable and widely available water quality data system is to focus our efforts on connecting existing hardware to our Caddisfly app, and making the app as user friendly and effective as possible. 

Consequently we have spun off a separate organisation called Foundation for Environmental Monitoring (FFEM), which is focused on creating environmental sensors and associated hardware.

Water quality test criteria 

In order to be effective and reliable, a water quality test kit needs to meet the following criteria:

  • Fit for all field settings, whether high or low-resource 
  • Simple to use
  • Affordable
  • Sufficiently accurate to be fit for purpose
  • Connected to a smartphone so the Akvo Caddisfly app can instruct the user on how to perform the test and upload the test result to the Akvo data platform.

Connecting hardware to Caddisfly

After a couple of weeks of work, we have already connected an existing photometer to Akvo Caddisfly. This covers a whole array of accurate colorimetric tests for drinking water, waste water, agriculture and environmental monitoring. We have also connected an innovative E. coli test that provides test results in line with World Health Organisation guidelines for E. coli risk categories.

Currently available Akvo Caddisfly tests are:

Colorimetry – Colorimetric tests work by assessing the colour of a water sample when combined with a specific reagent, and thereby determining the concentration of the contaminant in the sample. For our colorimetric test we have two options; a Caddisfly testing chamber (from FFEM) connected to a smartphone, or a proven and certified hand-held photometer that is connected to the Caddisfly app via Bluetooth. The photometer tests will be available in Akvo Flow in September 2017 (the testing chamber option is already available in Flow). Parameters that are currently available for colorimetric tests are: alkalinity, aluminium, ammonia, chlorine, chromium, COD, dissolved oxygen, fluoride, hardness, iron, nitrate, nitrite, nitrogen, pH, phosphate, potassium, sulphate, suspended solids and turbidity.

Test Strips – This is a simple and very low cost method for screen testing your water to get an indication of contamination. Available parameters are: arsenic, alkalinity, ammonium, chloride, free & total chlorine, hardness, iron, pH, phosphate, potassium, nitrate and nitrite. We are also pilot-testing the use of test strips for determining soil nutrients (NPK) and soil pH in multiple projects in South East Asia, you can read more about this here.

Sensors – We have developed and validated our own electrical conductivity (EC) sensor, which you simply dip in the water and read the result on your phone. This tells you the level of total dissolved solids (TDS) in the water, an indication of salinity. Moreover, we are looking at options to connect an existing dissolved oxygen sensor to our app. This provides an indicator of the suitability of water for wildlife.

Microbiology – We have connected an existing E.coli test that does not need an incubator, calculates the most probable number of E.coli per 100 ml, and provides results in accordance with WHO guidelines. This test will be available in Akvo Flow in September 2017.  Moreover we are looking at connecting an existing E.coli test that allows for colony-forming unit (CFU) counting per ml.

Data to decision

This whole range of parameters is part of our integrated system in which water quality data can form part of a broader smartphone-based environmental monitoring survey incorporating other important information to interpret the water quality data. All surveys with quantitative and qualitative information are sent to one online dashboard, allowing for rapid data analysis and decision-making, up to country or regional level.

It is Caddisfly’s integration with Akvo’s other tools for data collection, analysis, transformation and visualisation – combined with the range of water quality parameters that Caddisfly can test for – that means it’s very well placed to play a vital role in global efforts to monitor the achievement of the Sustainable Development Goals (SDGs). 

We’ll be showcasing Akvo Caddisfly, the different equipment it can connect with and the types of tests it can perform at World Water Week in Stockholm later this month. If you’re at the event, please drop by our booth for a demo or fix up a meeting. You can find us at stand 23 on the 2nd floor of the main exhibition hall.

Arthur Heijstek is project manager of Akvo Caddisfly, based in Amsterdam. You can follow him on Twitter at @arthur_heijstek.

Arthur Heijstek is the project manager of Akvo Caddisfly. He is based in Amsterdam and you can follow him at @arthur_heijstek