Field sampling for drinking water

All water will be collected at the point closest to the origination of that water supply prior to end- user treatment to minimize the time for S. Typhi or Paratyphi DNA to degrade in

water, if present. If the only option is to sample from water that has been stored, choose the

freshest (most recently stored) source.

Pre-label all Whirl-Pak bags with a fill line representing 1 litre of water

a. Fill a bag with exactly 1 litre of water in the lab. Mark the outside of the bag with a

line where the water reaches. Copy this line to the rest of the Whirl-Pak bags.

Place two duplicate random number stickers on the Whirl-Pak bag.

Put on gloves and ipen the bag, taking care not to touch the inside of the bag

Fill the bag with 1 liter or water

If necessary, ask the household member to turn on the water spigot so that you do not contaminate your gloves.

If the household uses water from a communal spigot, collect from this point

i. If a hose is connected to a communal spigot, remove it to collect directly from the tap

If the community spigot is not functioning/the water is not running, sample water from the house or building collection tank, using the sterile hand pump

If the storage tank in inaccessible, you can sample from stored water in a jug

i. Choose the freshest source of stored water (the one that was stored the most recently) ii.Avoid using a cup or container to transfer water from the jug If the container is too heavy to lift and pour into the Whirl-Pak bag, you can request to use the same cup or device the household uses to transfer water.

Close the bag with the pipe-locking device

Remove gloves

Scan the sample barcode into RedCap

If the code does not scan, manually enter it

Take a picture of the sample in the RedCap app, making sure that you can see the

barcode number

Place the full bag Whirl-Pak in an upright plastic bottle inside the cooler bag/backpack

Unused Whirl-Pak bags should be kept in a separate compartment from water

samples

Minimize opening and closing the cooler to maintain temperature control.

If maintaining temperature control is a challenge, consider placing temperature loggers

inside each cooler bag.