To dechlorinate water:
You can use a Water Filter (See Recommendations) or simply boil the water to remove the chlorine.
Make sure you let it cool to a lukewarm temperature before you use it, otherwise the heat will kill the beneficial bacteria, yeasts, and denature the phytase.
For the container:
But should a mason jar be unavailable and you must improvise, a large leftover glass pickle / jam jar is a great alternative. For other containers, use only ceramic, china, stainless steel 316, glass, or Polycarbonate, PP, HDPE, or LDPE Plastic containers only. A china bowl covered tightly with cheesecloth may also work, for example.
Other plastics and metals will react with the acidity and interfere with the natural processes of fermentation. Plus, they may leech harmful chemicals. For example, non-steel metal containers will rust, and many plastics release BPA and other chemicals.
SAFETY FIRST - Monitoring the smell and keeping an eye out for mould:
The smell is different for every starter, and can often be:
This is subjective, but always monitor for any particularly unpleasant odours that might suggest unwelcome bacteria (like a sulphuric, pungent, or highly displeasing smell). Personally, almost every starter I have made smells like a yeasty, soured dough with a vinegary undertone.
You should also keep and eye out for any mould from day 1 - there should be no colourful, white, black, fluffy, or otherwise mould-descriptive growths. If there are any, or if the smell is noticeably unpleasant, you will need to start the process again.
The exception here is something called 'kahm yeast'. Kahm yeast is a filmy, slimy yeast naturally present in the air, and can inhabit lacto-fermented foods. It is not toxic like mould, and can safely just be removed. It isn't encouraged, however, as it may be suboptimal for fermentation and have an undesirable affect on taste.
For reference images and more information, Fermenting for Foodies has a wonderful article that dives into the details.
- Slightly vinegary
- Or even resemble "slightly old socks"...