FAQ
How WaterWatch works
This page explains how WaterWatch works and the rules behind what you see on the map. The aim is to be open about how decisions are made, so you can judge the information for yourself and question it.
The map
How the map works
Which waters does WaterWatch cover?
Three views you switch between at the top of the map: Open water (rivers, lakes and coast), Bathing (designated swimming waters and community-added spots), and Drinking (public water supplies). Each has its own status scale. You can add reports on Open water and Bathing; Drinking is view-only, showing official monitoring.
What do the colours mean?
Colours depend on the view. Open water uses the official EPA Water Framework Directive scale: High, Good, Moderate, Poor and Bad. Bathing uses the EU bathing-water scale: Excellent, Good, Sufficient and Poor. Grey means no official rating or no data yet, including a community spot with no citizen reports so far.
What is a community bathing spot?
A beach or swim spot that is not one of the EPA-designated bathing waters. It is shown with no official rating, carrying only citizen reports until enough of them agree. If your usual spot is not listed, you can add it by name when you make an observation.
Where does the information come from?
Two kinds of source. Official monitoring, from the EPA in the Republic of Ireland and DAERA in Northern Ireland. And reports from members of the public who have seen the water in person. Both are shown on the same map.
How are official data and public reports combined?
Official monitoring is the starting point wherever it exists. Public reports are added to it. Official data can raise or confirm a concern at any time. A public concern only changes the colour of a water body once more than one person has reported it with supporting evidence. A single public report never repaints a named river on its own.
Why are only some rivers shown on Drinking water, and what do the colours mean?
The Drinking view shows only the public water sources the EPA monitors: designated abstraction rivers, lakes and groundwater, not every river. Private wells (about 12% of supplies) are unmonitored and not shown. A source shows as “Not flagged” in a neutral slate when it is not on the EPA’s Remedial Action List. That is a regulatory status, not a verified water-quality test, so we do not paint it a confident green. Supplies on the list show as At risk or Action required. Northern Ireland sources show grey, because compliance is not published there as open data.
Getting started
Making an observation
What is an observation?
An observation is a note you add about water you have seen in person, at a place and time. It can be as simple as what the water looked like, or it can include a photo or a test result.
How do I make one?
On the map, tap or click a place to open a card showing what is known about that location. To start your own, use the Add an observation option shown, in that card or at the top of the screen. For a beach, tap it and choose "Add an observation here", or use Add an observation and then Set location on map to drop the pin yourself. Choose what you saw, add a photo if you have one, and submit. You can report with or without an account. On a touchscreen, you can also press and hold a spot to begin an observation there.
Your reports
Public reports and how much they count
Who can submit a report?
Anyone. You can report anonymously or with an account, and both count. Reports can be added on Open water and Bathing, but not on Drinking water, which is shown for information only.
Does one report change the colour of a river?
No. A single report shows as a pin and is marked as needing confirmation. It does not change the colour by itself. This stops one mistaken or bad faith report from labelling a named river.
How many reports are needed to change a colour?
At least two independent reporters, and the reports need real supporting evidence, not just two reports with nothing to back them up. So two people who photograph a pollution problem will change the reading. Two empty reports will not.
What does "needs confirmation" mean?
When there is a report but not yet enough to confirm it, the water body keeps its current colour and shows a short note, for example "1 of 2, needs confirmation", along with the pin. When a second independent report with evidence arrives, the reading updates. This works the same for good reports and bad reports.
How is the strength of a report decided?
By how much supporting evidence it carries. A short written note counts the least. Adding a photo, structured details, or a verified test kit result each raises how much the report counts.
What stops people faking reports?
Several things together. A reading needs more than one independent person. Reports need supporting evidence to count, so a pile of empty reports achieves nothing. Repeat reports from the same person at the same place on the same day count once. And anyone can flag a report they believe is fake, which sends it for review.
Balance
Positive and negative observations
Can I report that water looks clean, not only polluted?
Yes. You can make a positive observation as well as a negative one.
Do positive observations cancel out negative observations?
No. Positive and negative observations are never averaged against each other. A run of "all fine" observations cannot bury a confirmed problem. This is deliberate, so a real concern cannot be hidden behind positive observations.
Freshness
How fresh the information is
Does a report lose weight over time?
Yes. A report counts for most when it is recent, and its weight fades gradually, halving about every 30 days. Older reports are not thrown away straight away, they count for less.
What happens when the official assessment is old?
It depends on the water. For designated bathing waters, where the agency publishes each sample date, the card shows when the water was last tested, for example "Last tested 21 July 2026". For rivers, lakes and coastal waters, the official ecological status is a multi-year survey with no single test date, and drinking-water supplies publish no test dates as open data — so there the card shows when WaterWatch last checked the reading, for example "Last checked 1 May 2024", and marks it when that is more than three years ago so you can see it may not reflect the water today. When newer confirmed public reports disagree with an old official reading, the app shows that the public reports are updating a dated official assessment.
Why show old official data at all?
Because it is still the most authoritative information available for that water body. Rather than hide it or present it as current, the app shows it and shows its age.
Privacy
Privacy
Is my exact location shared when I report?
No. Report pins are shifted by a short distance, about 250 metres, so a report never points to an exact spot such as a home.
Do I have to give my name?
No. You can report anonymously. The public view never shows a reporter's identity or the exact time of a report.
Coming next
What is planned next
Will weather be included?
It is planned. Heavy rain can affect water quality, so weather information will help separate short lived events from ongoing problems.
Will sensors or monitoring devices be supported?
It is planned. The app is being built to accept readings from fixed monitoring devices in future, so live sensor data can sit alongside official and public information.
Can official bodies use this?
Yes. The information is open. Local authorities and other official bodies see the same map as everyone else, which can help them decide where to test.
Background
Why WaterWatch exists
Why was the app built?
I built WaterWatch after taking my children to nearby beaches and rivers where I could visibly see the water was not clean, and it made me question where we could or could not swim. I wanted a way to check a recent picture of the water before we set out, instead of finding out when we arrived. There is also a wider need for this. An interview on RTE Radio 1's Countrywide discussed the case for an app of exactly this kind.
If you want to question any of these rules or suggest a change, please get in touch through the Contact page.