Android phones and Android tablets only. The PQWT M-series app does not work on Apple iPhone or iPad (iOS / iPadOS). A physical PQWT M100, M200 or M400 instrument collects the survey signals; the connected Android device displays the app, curves and profile map. Download the APK, operation video and English, Spanish or Russian manual below. The app alone cannot detect groundwater.
This guide follows the supplied PQWT-M100 / M200 / M400 operation manuals. It brings the installation files, field workflow and original training video together for operators preparing a new instrument or reconnecting an existing one.
Start by checking your Android device and instrument model. Then complete a short connection, recording and file-storage check before travelling to the survey site. The manual illustrations use M100 as the example; choose the matching instrument name when you use M200 or M400.
Download the M-series operation video, app and manuals
Watch the original 4-minute 22-second operation video here, or save it as an MP4 for offline training. The PDF manuals and app files are available separately, and the complete ZIP pack contains the video, all three manuals, the Android APK and a getting-started note.
All M-series training files
Operation video, English / Spanish / Russian manuals, Android APK and a getting-started note.
ZIP · 17.68 MBDownload complete pack ↓Operation videoPQWT-M Mobile Water Detector
Original operation video for instrument setup and the mobile survey workflow.
MP4 · 4 min 22 sec · 14.77 MBDownload video ↓Android onlyPQWT Android app APK
For Android phones and Android tablets. Not compatible with iPhone or iPad.
Supplied v1.0.8 package · 1.01 MBDownload Android APK ↓Android app archivePQWT app in ZIP format
Contains the same APK as the direct download. Extract the ZIP before installing on Android.
ZIP · 742 KBDownload app ZIP ↓EnglishM-Series Operation Manual
Illustrated M100, M200 and M400 setup, Android app installation, measurement and data storage.
12 pages · PDF · 700 KBDownload PDF ↓EspañolManual de operación para la serie M
Instalación en Android, conexión Bluetooth, mediciones, almacenamiento de datos y cableado.
4 pages · PDF · 291 KBDownload PDF ↓РусскийРуководство по эксплуатации PQWT-M
Установка приложения Android, подключение, измерения, сохранение данных и схема электродов.
13 pages · PDF · 1.58 MBDownload PDF ↓Which phones and tablets can use the PQWT M-series app?
The supplied manuals specify Android but do not provide a tested compatibility list for every device or Android release. If the app does not install or connect, send support your phone or tablet model, Android version and the exact message. Do not assume that every Android device has been verified with this package.
A phone is the display and control interface. It must connect to the actual M-series instrument to receive measurements. Viewing this guide, reading a PDF or playing the MP4 on an Apple device does not make the Android app compatible with that device.
| Device | App support | What to check |
|---|---|---|
| Android phone | Supported platform | Bluetooth, the required app permissions and permission to install the supplied APK. |
| Android tablet | Supported platform | Bluetooth and Android APK support; confirm connection and recording before fieldwork. |
| Apple iPhone | Not supported | The supplied APK is an Android application and cannot run on iOS. |
| Apple iPad | Not supported | The supplied APK cannot run on iPadOS. |
How to install the PQWT Android APK
Download on your Android device
Use the Android APK button above. If you downloaded the app ZIP instead, extract it and locate the APK inside. Do not rename the ZIP extension to APK.
Open the installation file
Open the APK from the browser download list or Android Files app. If Android asks, allow this browser or file manager to install the package from this source. Menu wording varies by device.
Review the installation prompts
Keep Google Play Protect enabled. If Android reports an unsupported version, a harmful-app warning or an installation block, contact support with the exact message rather than disabling the device's protection.
Open PQWT water finder
Start the installed application. When installation is complete, the temporary permission for your browser or file manager to install apps can be turned off again.
Connect M100, M200 or M400 to the app through Bluetooth
The manual describes field measurement without internet access or mobile data once the app is installed. Bluetooth still needs to remain enabled for the local instrument connection. Download the manuals and video before leaving internet coverage.
- Connect the instrument accessories as shown in the manual, then press and hold the white power button to turn on the host.
- Turn on Bluetooth and Location services on the Android phone or tablet. Open the PQWT water finder app.
- Allow the Bluetooth and Location permissions requested for device discovery. On Android versions that show Nearby devices, grant that permission when requested. Permission names depend on Android and the app version.
- Select your instrument from the app scan list. The manual example uses PQWT-M100; choose the corresponding model for your own host.
- Wait until Connected appears at the upper right before opening Settings or starting a measurement. Complete a short test recording to confirm that data arrives.
Electrode spacing, line test and measurement workflow
The manual describes each recorded measurement as the midpoint between two electrodes. Its usual electrode spacing is 10 m, with a point advance of 1–5 m and a standard example of 1 m. Electrode spacing and point advance are different quantities: keep each consistent throughout one survey line.
Plan the survey line
Use a line that avoids high-voltage infrastructure and abrupt elevation differences. Record the line direction, starting reference and electrode spacing. The manual recommends more than 15 measurement points on one line.
Check the measuring circuit
With the measuring leads connected, put the two copper electrodes in contact and press TEST as described in the manual. A green line-test indicator shows a normal circuit in this test; an unlit indicator requires checking the circuit before surveying.
Place the electrodes
Separate the electrodes to the planned spacing and establish consistent ground contact. For the manual's 10 m spacing and 1 m point advance, move both electrodes forward by 1 m between completed recordings. The first midpoint is 5 m from the initial electrode position.
Select the measurement mode
Once connected, open Settings, choose the survey line and mode, and confirm. The manual example starts with line 1 and default Gain 0. Three-frequency mode is used for a preliminary comparison; follow promising sections with a profile survey.
Record without moving
Tap Record, keep both electrodes still, and wait for the completed-recording message. Only then advance to the next point. Use the same stepwise procedure for a profile survey and check the curve and profile as the line develops.
Repeat and assess the result
Check repeat measurements and nearby profiles before interpreting a target. A low reading or a colored anomaly is an indication for investigation, not proof of groundwater, its quantity or a successful borehole.
Where are M-series survey files stored?
The supplied manual shows a PQWT folder in the Android device's internal storage. It illustrates separate Three Freq and Profile Survey folders, with survey lines such as L1 and L2 inside. Look for the relevant line when reopening or sending a measurement record.
Android storage access and folder visibility can differ by device and system version. If a file is not visible, check the app's requested file/storage permissions and ask support for instructions for your Android version. Confirm a test file is saved before a full survey, and keep a backup before changing phones or uninstalling the app.
- Keep the original survey files alongside any screenshot of the curve or profile.
- Note the instrument model, line direction, electrode spacing, point advance and ground conditions.
- When requesting interpretation help, send the original line files and layout details so the team can understand where each record came from.
Common installation, Bluetooth and recording questions
| Problem | Checks to make |
|---|---|
| The instrument does not appear | Check host power, phone Bluetooth, Location services and the permissions requested by the app. Bring the phone close to the host, then reopen the scan list. |
| The app is open but not connected | Select the correct model in the app and wait for Connected. Do not begin recording while it is still searching. |
| Android will not install the APK | Confirm that the file is fully downloaded and extracted if using ZIP. Record the exact warning, phone model and Android version, then contact support. |
| The file opens as a ZIP | Extract the archive and open the APK inside on an Android phone or tablet. The ZIP is a transport format, not a separate app. |
| The line-test green light stays off | Check measuring leads and connections and repeat the manual's test with the copper electrodes touching. Ask support if the circuit still fails. |
| Saved data cannot be found | Check the PQWT folder and the correct mode/line folder shown in the manual. Review the requested storage permissions and preserve existing files. |
| I have an iPhone or iPad | Use a compatible Android phone or tablet for the instrument app. Apple devices can still read the manuals and play the operation video. |
Which models does this M-series guide cover?
These are the manufacturer's stated ranges, not guarantees of groundwater occurrence or drilling success. Select the range from the geological target, survey conditions and project plan. Confirm any proposed borehole with appropriate geological evidence and field verification.
| Model | Stated investigation range in the manual | Mobile interface |
|---|---|---|
| PQWT-M100 | 100 m | Android phone or tablet |
| PQWT-M200 | 200 m | Android phone or tablet |
| PQWT-M400 | 400 m | Android phone or tablet |
M100 mobile survey instrument
Review the 100 m stated range, instrument package and project requirements. Android phone/tablet app required.
View product →
M200 mobile survey instrument
Review the 200 m stated range, instrument package and project requirements. Android phone/tablet app required.
View product →
M400 mobile survey instrument
Review the 400 m stated range, instrument package and project requirements. Android phone/tablet app required.
View product →Sources and editorial note
Written as an original technical guide using the source material below. Product suitability and field results still depend on site conditions, operator technique and independent verification.
- PQWT-M100 / M200 / M400 Operation Manual (English) — Supplied manual: Android installation, measuring steps, field precautions, storage and wiring; first edition 2025.
- Manual de operación para la serie M (Español) — Supplied Spanish installation and operation instructions.
- PQWT-M Operation Manual (Русский) — Supplied Russian instrument, measurement and wiring instructions.
- Android Bluetooth permissions — Explains why Bluetooth and device-discovery permissions differ by Android and app target version.
- Google Play Protect — Google's guidance on app checks and keeping Play Protect enabled.
Frequently asked questions
Can I use the PQWT M-series app on iPhone or iPad?+
No. The supplied PQWT M-series app is for Android phones and Android tablets only. It does not run on iPhone or iPad. Apple devices can view the PDFs and MP4 video, but cannot operate this Android app.
Where can I download the M100, M200 and M400 app and manuals?+
The M-series download center on pqwtofficial.com provides the Android APK, an alternative ZIP containing the same APK, English, Spanish and Russian PDF manuals, and the original operation video. A complete ZIP pack contains the APK, all three manuals, the video and a getting-started note.
Does the app work without a PQWT instrument?+
The app is the instrument's display and control interface. It needs a physical M-series host and the correct survey accessories to collect data. A phone or tablet running the app alone cannot detect groundwater.
Is internet required during a survey?+
The supplied manual describes field measurement without internet or mobile data after installation. The Android device still needs its Bluetooth connection to the instrument. Download training files before working offline.
Why does the app ask for Location permission?+
The M-series manual requires Bluetooth and Location permissions for device discovery. Android permission behavior varies by operating-system and app version; follow the relevant device-discovery prompts, including Nearby devices when requested.
What spacing should I use between the two electrodes?+
The manual normally uses 10 m electrode spacing and a 1–5 m point advance, with 1 m as the standard example. Keep both settings consistent along the line. Each measurement represents the midpoint between the electrodes.
Is the APK in the ZIP different from the direct APK?+
No. The supplied ZIP contains the identical Android APK. It is an alternative download format; extract it before installation.
Does a low reading prove that water is present?+
No. Review repeatable profiles, site conditions and geological evidence. An anomalous reading does not by itself confirm groundwater, water yield or the success of a borehole.
PROJECT REVIEW & MODEL SELECTION
Need help with your M-series setup?
Send your instrument model, Android phone/tablet model, Android version and a screenshot of the connection or installation message.