Table 1 Rainfall variable calculations and sources

Total monthly rain

Total rainfall in the 30 days prior to the survey: Sum of daily rainfall in last 30 days prior to the survey

RMI-MD

Access to water: High rainfall (continuous pattern): Individuals using surface or pump water may switch to rainfall water during periods of heavy rainfall especially if water is inaccessible. High rainfall (downpour pattern): People using tap water may experience interruptions in water supply during heavy rains because silt in the water can clog filters at treatment plants.Low rainfall: Households that rely on surface water or tap water (treated surface water) sometimes experience water shortages during periods of no rain, especially during periods in which rain is expected.

Quality of drinking water: High rainfall (continuous or downpour pattern): Heavy rainfall may contaminate surface water by carrying waste and sediment into water sources used for drinking.Low rainfall: Low rainfall may force people to use contaminated water sources that they would not normally access.

Quality of toilet: High rainfall (continuous or downpour pattern): With adequate water people may engage in more vigorous cleaning. Low rainfall: Very low rainfall (drought) may compromise cleaning and sanitation.

Quality of stool disposal: High rainfall (downpour pattern): If stool is not disposed of adequately, heavy rain might wash away contaminated material away from the vicinity of the household. High rainfall (continuous pattern): If rainfall prevents normal mobility, stool may be disposed of nearer the household.

Shared toilet: High rainfall (continuous or downpour pattern): Cleaning may be facilitated by the availability of water. Low rainfall: conversely, lack of water may prevent adequate sanitation.

Runoff water

Total run off in mm/month the previous month: The sum of the runoff in the month prior to the date of data collection.

NOAA

Quality of drinking water: Runoff water and flooding can lead to the contamination of surface water. Sediment in surface water can clog filters in water treatment plants and cause short-term interruptions in city water supply.

Quality of toilet: Runoff water cleanse the environment of contaminating feces. However, low run off may create stagnant pools that foster the growth of harmful micro-organisms.

Monthly rainfall intensity

Rain for the month compared to the rain for the year: average daily rainfall for 30 days prior to the survey minus average daily rainfall for 365 days before the survey. A measure >0 means the month was wetter than the annual average.

RMNR-MA

Access to water: Rainy season: Individuals who use surface or pump water may use water from rainfall during wet months. Piped water may be interrupted during the rainy season because increased silt in the water can clog filters at the treatment plant. Dry season: Households that rely on surface water or tap water (treated surface water) sometimes experience water shortages during the dry season.

Quality of drinking water: Rainy season: During the rainy season runoff and agitation by rain can decrease water quality by introducing silt and waste into surface water. Households that switch to rainwater during the rainy season, however, generally do not experience a decrease in water quality. Dry season: During the dry season, people who rely on surface water may experience a decrease in water quality.

Quality of toilet: Good toilets are only effective if they are cleaned. Dry season: If the household is short of water, toilets may be less well cleaned.

Quality of stool disposal: Rainy season, drier annual average: If it is a rainy time of year, some parents may not dispose of their children’s stools properly in latrines and rather dispose of stools directly into the environment close to the house.

Anomalous rainfall

The rain for last 6 months compared to the long-term rainfall in the corresponding 6 months for the previous 30 years:

Sum of the daily rainfall for last 180 days minus sum of rainfall for full year from decadal estimates divided by two. A measure less than 0 mean that there was less rainfall for the 180 days than expected based on the long-term rainfall.

RMNR-MA, FEWS

Access to water: When water is available people may use it without looking for water from an improved source. Households plan their water storage and usage based on past experience of weather patterns, for example storing large quantities of water for the dry season and rationing it until the rains are expected again. If a rainy season does not produce as much water as expected, or if a dry season lasts longer than expected, water shortages may occur and result in poor hygiene, and under consumption of water.

Quality of toilet: Families try to store enough water to get through expected dry seasons, though if the dry season is longer than expected or comes earlier than expected, families may face water shortages and reduce good hygiene practices, such as cleaning the toilet, because water is being used sparingly for other purposes.

Shared toilet: If the rainfall is less or more than expected, families may face issues regarding their behaviors like hygiene practices, such as cleaning the shared toilet, because water is being used for other purposes or because the shared toilet is dirty due to mud from outside. Unexpected rain may influence increased need for water consumption or careless hygiene that may influence diarrhea transmission.