# A Review of In-Situ and Remote Sensing Technologies to Monitor Water and Sanitation Interventions
###### Abstract
In this paper, we review the landscape of technologies, methods, and approaches that can support and improve on the water and sanitation indicators proposed for SDG targets 6.1 (\"By 2030, achieve universal and equitable access to safe and affordable drinking water for all\") and 6.2 (\"By 2030, achieve access to adequate and equitable sanitation and hygiene for all and end open defecation, paying special attention to the needs of women and girls and those in vulnerable situations\"). In some cases, technologies and methods are proven and readily available. In other cases, emergent technologies and approaches hold promise but require further field evaluation and cost reductions. In any case, considering which emergent technologies will most effectively monitor progress toward the SDGs is of critical importance as stakeholders seek to identify which kinds of policies and programs are working well, and which require corrective measures. Efforts to measure the adoption of and compliance with key water and sanitation technologies--such as latrines, water pumps, and water filters--have often relied on surveys and field observations. Despite what some consider to be the gold standard in WASH monitoring and evaluation, structured observation still has substantial limitations. For one, implementation is resource intensive, requiring time, labor, and funds. Quality enumerators and comprehensive training are required to limit bias due to respondent reactivity and observer differences. This is especially important when the measurement is fairly subjective--inclusive of not only self-reported behaviors and proxy indicators, but also those dependent on observer interpretation--as this has been shown to bias effect estimates [4]. Secondly, the length of time the observer is in the household may be inconvenient for study participantsand may change their routine [5]. Thirdly, similar to survey reactivity, the act of repeated observation has been shown to augment the behavior of interest, known as the Hawthorne effect [6]. The presence of a human observer outside of a latrine modifies the usual behavior of households, increasing the use of the latrine significantly [7]. Similarly, one study showed soap use after crucial events is higher in the first 90 min of observation than in the following three and a half hours [5]. Additionally, households with higher social status show more reactivity to the observer, meaning the exercise may capture information about the population differentially [8]. Finally, direct observation has been shown to have low repeatability in individual monitoring and may only be appropriate to measure behavior at a population level or after repeated observations [9], although the latter has the potential to produce a Hawthorne effect as well. While the new SDG indicators for WASH build on established indicators, thereby providing some continuity that will help ongoing monitoring efforts, they also move beyond them. This places considerable demand on national household surveys to develop new data collection methodologies. Emergent technologies--including water meters, water pump sensors, and latrine motion detectors--can improve the objectivity of data collection. Satellite-based remote sensors linked to the Internet of Things can be aligned with smartphone-based surveys and online \"big data\" tools. In addition, high-resolution smart water meters and advanced data analytics allow for a new era of using the continuous \"big data\" generated by these meter fleets to create an intelligent system for urban water management. These technologies can also provide more transparency and accountability means from governments when delivering these types of services to the population. Governments fulfil this responsibility by using evidence and updated data for planning, regulating, financing, budgeting and monitoring services and providing information about them. Government decisions depend on the extent to which information is reliable and monitored on a timely basis, to also underpin the service delivery arrangement.