Water Quality Monitoring & Testing

Water Monitoring

Read about our water quality monitoring

Water Risk Map

Explore our interactive map

Water Testing

Get your water tested

Water Quality Monitoring

One of the main areas of Caminos de Agua's work is to continually test water from wells and taps in the Independence Watershed region, in order to monitor the changing water quality in the region.

We provide water quality testing services to a variety of different groups. We offer free testing for urban and rural community drinking wells and other community sources in the region, and to various study groups. We charge private clients a small fee to ensure we can continue to carry out this work into the future.

We also work on water quality monitoring studies in partnership with various Mexican and international universities and institutions. Since 2012, we have collaborated with groups such as the University of Guanajuato, Texas A&M University, Kansas State University, Northern Illinois University, and CODECIN (Coalition in Defense of the Independence Watershed) to undertake such studies.

We try to make the water quality data that we find as open-source and freely-available to the public as possible, to allow you and your neighbours to see the water quality in your area. We publish most of our data on our interactive water risk map of the region, explorable below.

Water Risk Map

For the best viewing experience, we recommend NOT using Safari to explore this map.
Chrome, Firefox, Explorer, Opera and Edge all offer excellent browser viewing experiences. Double-click or 'shift-click-drag' to zoom into certain regions.

The interactive maps above highlights the risk presented by arsenicfluoride, or a combination of the two contaminanats ("total risk") throughout the region. This data has been collected by Caminos de Agua as part of their water quality monitoring studies and water quality testing services.

For healthy drinking water, the permissible limit of arsenic given by the Mexican Standard (Modificación a la Norma Oficial Mexicana NOM-127-SSA1-1994) is 25 µg/L (or 0.025 mg/L). However, given that the results of recent investigations show the serious health consequences of excess arsenic, Caminos de Agua considers this limit to be outdated (it was last updated in 2005) and too high, and so we follow the standard given by the World Health Organization (WHO) (Guidelines for drinking-water quality, 4th ed., 2011), which gives a maximum recommended value for arsenic of 10 µg/L (or 0.01 mg/L).

For fluoride, the permissible limit given by the Mexican Standard and the maxiumum recommended value given by the WHO are both 1.5 mg/L.

Several of the data points in San Miguel de Allende were provided by the municipal water authority (SAPASMA).  Caminos de Agua cannot guarantee the accuracy of this data. The locations of the SAPASMA sites are also estimated, as exact coordinates of the wells were not provided.

If you would like to have your water tested, please scroll down for more information on water quality testing.

Also, if you live in San Miguel de Allende and can see that your colonia does not contain any points, we may offer to test your water for free every few months, as part of our ongoing Urban Water Quality Monitoring Program (UWQMP). Please email us at lab@caminosdeagua.org if you are interested.

Water Quality Testing

As part of our water quality monitoring program, Caminos de Agua provides water quality testing services to a variety of different groups. We test water in our lab in San Miguel de Allende, and water quality results are shared on our interactive water risk map (if the client gives permission for their data to be shared), so that everyone can explore the water quality in their neighbourhood.

We offer free testing to study groups, community groups and to certain other groups who have made special alternative arrangements, to allow us to better monitor the water sources that serve large numbers of users. If you are testing any water source where many people's health may be affected and/or if you are unable to pay, we may be able to test for free.

Private clients are charged a fee for their testing – money that helps us to ensure we can continue to do the work we do.

Who do we test water for?

  • Private clients, who are testing treated or untreated water from a private residence, private well, or the bottled water they use.
  • Local study groups, such as our Urban Water Quality Monitoring Program (UWQMP).
  • Urban and rural community groups, or anyone testing a water source that serves a community, for example a community well, water refill station or water treatment plant.
  • Anyone else who has contacted us to make special alternative arrangements for testing. Please contact us at lab@caminosdeagua.org if you do not feel that you fall into one of the groups above, and would like to make alternative arrangements for testing.

How can I get my water tested?

To get your water tested through Caminos de Agua, you'll need to complete the following four steps. Please scroll down through this page to explore these steps, or click on one of the steps in the list below to jump straight there.

  1. If testing as a private client, then first consider which type of testing you would like.
    (If you are part of a local study group, community group, or if you have made special alternative arrangements for testing, continue to step 2.)
  2. Complete an online form to send us your details
  3. Collect your sample(s)
  4. Drop off your sample(s) at our lab

Step 1 – Consider which type of testing you would like

Full Test (ARSENIC, FLUORIDE, Total Dissolved Solids, PH)

Cost: 750 Mexican Pesos
Processing time: 2 weeks
Description: This test covers the two most commonly-occurring mineral contaminants in the region – arsenic and fluoride – as well as giving information on the amount of total dissolved solids and the pH.

(This is the test carried out by default on samples sent to us from urban and rural community groups, members of local study groups such as the UWQMP, and others who have made special alternative arrangements for testing with us.)

Quick Reverse Osmosis (RO) system efficiency Test

Cost: 200 Mexican Pesos
Processing time: 24 hours
Description: This test is for people with a reverse osmosis (RO) water treatment system, who want to make sure their system is working correctly.  The test does not give results on the levels of specific contaminants like arsenic and fluoride, but it does give a quick result showing the total quantity of dissolved solids (which includes mineral contaminants such as arsenic and fluoride) in the water before and after the RO system, and the overall efficiency of the system at removing these dissolved solids.


Cost: Dependent on request.
Processing time: Dependent on request.
Description: We are able to test for other contaminants upon special request. We have the capacity to test for total coliforms and E. coli (a potentially harmful fecal coliform) using the widely renowned IDEXX Quanti method, which is used as standard by governments around the globe. We are also able to test for nitrates, which may present a problem in surface water in high-intensive agricultural areas. Such tests can also be combined with one of the tests above, on special request.

Bacteria testing alternatives: If you are looking to test for bacteria, you may find it quicker and easier to test through another lab in San Miguel. Click here for a list of options.

Step 2 – Complete an online form to senD us your details


Please note, if you would like to test your water through Caminos de Agua's Lab, you may need to know your GPS coordinates.
Please click here for more information on how to find your coordinates.

Step 3 – collect your sample(s)

Once you have completed the online form above to send us your details, then you're ready to collect your water sample(s)! Here are the instructions for how to collect them:


- participants of the uwqmp,

  1. Find a container: Find an empty PLASTIC bottle or container with a capacity of 1 litre or more. A normal water bottle is fine. It does not need to be new, but it must be plastic.
  2. Let water flow: Turn on the tap (or sample water source) and let it run for 2-5 minutes, if you can.
  3. Clean the container: Half-fill the container with sample water, cap the container, and shake it vigorously to clean. Repeat this 3 times.
  4. Fill the container: Fill the container with sample water and cap it tightly.
  5. Label the container: Write the following on the container in permanent marker: your name, the first line of your address, and the date the sample was taken, and a brief description of the water sample (e.g. "treated kitchen water - reverse osmosis system" / "UWQMP" / "community well water").
  6. (If you are submitting multiple samples for testing): Repeat these steps for each sample you would like to submit for testing.


PRIVATE CLIENTS WHO CHOSE Quick RO system efficiency Test

  1. Find two containers: Find two PLASTIC OR GLASS bottles or containers with a capacity of at least 100 mL each (but preferably at least 500 mL). A normal water bottle is fine.  They do not need to be new, but they must be plastic or glass. One container will contain pre-filter water (water from the normal tap) and the other will contain post-filter water (water that has been treated by the filtration system you want to test).
  2. Let water flow: Turn on the tap (or sample water source) and let it run for 2-5 minutes, if you can. Do this for both the pre- and post-filter water sources if possible.
  3. Clean the containers: Half-fill the container with the relevant sample water, cap the container, and shake it vigorously to clean. Repeat this 3 times. Do this for each container, using the relevant sample water for each.
  4. Fill the containers: Fill each container with the relevant sample water and cap them tightly.
  5. Label the containers: Write the following on each container in permanent marker: your name, the first line of your address, the date the sample was taken, and whether the container contains normal tap water (write "pre-filter") or water treated by your filtration system (write "post-filter").

Step 4 – Drop off your Sample(S) at our Lab

Once you have submitted your details using the online form above, and collected your sample(s), then you're ready to drop off the sample(s) at our lab!

All water samples should be dropped-off on TUESDAYS BETWEEN 2 PM AND 5 PM. There is no need to book an appointment. Please do not come at another time, as there may not be anyone at the lab to receive your sample(s). If coming at this time is a problem for you, then please contact us using the details below.

If you chose to pay by cash when submitting your details, then please remember to bring cash with you when you come. Exact change is appreciated.

No samples will be tested unless an online form has been completed, and the sample container is correctly labelled (as detailed here).


Caminos Lab – Contact Details and Location

Federico Montes de Oca 2-C
Colonia Independencia
San Miguel de Allende

(415) 154-1102