Table 1 Indicators for SODIS-use

1.

"Bottles sun-exposed"

Proportion of weeks during which SODIS bottles were observed to be exposed to sunlight (as observed by community-based staff)

Indicator for the intention to disinfect water using SODIS. Indirect indicator to measure actual use.

2.

"Bottles ready-to-drink"

Proportion of weeks during which SODIS bottles were ready-to-drink (as observed by community-based staff)

Households regularly disinfecting water with SODIS usually have bottles of SODIS-treated water ready-to-drink available in-house. Considered to be a more reliable indicator for actual use than "bottles exposed to sunlight"

3.

"Classified user"

Proportion of weeks during which a family was classified as SODIS-user (judgement of community-based staff after observing the family for at least 4 weeks).

Considered the most reliable indicator for actual use. Staff living in the community bases their judgement on daily observations of correct application, placing bottles in plain sunlight and/or getting drinking water from a SODIS-bottle when asked for.

4.

"Behavioural change"

Regression coefficient of a logistic regression of the occurrence of bottles exposed to the sunlight (yes/no in a given week) versus time.

Indicates behavioural change over time. Coefficient reflects an increase (high values), decrease (low values) or constancy of exposing bottles to sun throughout monitoring time. Note: a coefficient of B = 0 indicates constant SODIS-use at high or low levels

Monitoring indicators

5.

"Time in Study - Bottles sun-exposed"

Total number of weeks during which "Bottles exposed to sunlight" was recorded

Discriminates and identifies households with few weeks observed.

6.

"Time in Study - Classified user"

Total number of weeks during which "Classified user" was recorded

Discriminates and identifies households with few weeks observed to classify as SODIS-user.