Many people interested in measuring various **water quality parameters** that are relevant to environmental health in low-cost and accessible ways. Many have been working on low-cost, open-source sensors for water chemistry and physical properties, and there are also several commercially available water sensors and analog tools that can measure relevant water quality parameters. ### Sensors, Loggers, Enclosures Often, electronic environmental sensors are just one part of a system that includes: * a [data logger](/wiki/data-logging) * some kind of [water and weather-proof enclosure](/wiki/sensor-enclosures) * a **sensor of some kind** -- see [Sensors](#Sensors), below **** ## Questions [questions:water-sensors] **** ## Sensors Often the first step is to **look for a sensor for what you're hoping to measure.** Below we're collecting info on different kinds of water quality sensors, and their: * cost * sensitivity/accuracy * links and documentation See and [edit the full spreadsheet here](https://docs.google.com/spreadsheets/d/1UwjRqU8kHTwEcnDdO2Zxkr8zkFkaGfyePJ-cdnxJzw0/edit?usp=sharing) (See this [list of sensors from the KnowFlow](/questions/rockets/07-10-2017/how-accurate-is-the-probe) as well!) Are there others you're interested in? Please add them to the list here and to the linked Google Doc! - flow rate - temperature - depth/pressure - Transparency - colorimetry - dissolved oxygen - ammonia/ammonium - oxidation-reduction potential - ORP - chemical oxygen demand - COD - Phosphate - conductivity/salinity - total dissolved solids - TDS - turbidity/TSS - pH - Hardness - Lead - nitrate - bacteria - Fluoride [prompt:text:ie temperature] **** ### Analog methods Even though this wiki page is labeled "water sensors," the most accessible modes of measuring water quality parameters are often **analog, non-digital methods** where you directly observe water (e.g. using a secchi disk to assess turbidity) or collect a sample and test it with a visual method (e.g. color-change pH strips). Several analog tools are included in the spreadsheet, and please add more! ### Hybrid approaches and enclosures In some cases, it may be possible to couple a commercially available **probe** sensor with a DIY **data logger** (such as the Riffle, https://publiclab.org/riffle) and an water-tight **enclosure** to create a lower-cost deployable sensor. Deployable sensors can be extremely useful for long-term monitoring, monitoring in places that are difficult to access frequently, or to document fluctuations in water chemistry with greater temporal resolution.