In the Annual Report of the Board of Health for the City of Lowell for 1890, five sources of water supply for the city are listed. The Board supported Sedgwick's opinion that chemical examination of the water was
unreliable and emphasized that bacteriological testing was needed. The five sources for Lowell's water were:
1) The Merrimack River. The city water was taken from the river a short distance above the Pawtucket dam and distributed from reservoirs through the city's
2) Canal water. This was river water drawn just above the dam into two large canals which supplied power for about ten large manufacturing corporations. Some of the corporations also pumped canal water into their mills for water-closet and washing purposes. Although the use of this water was forbidden for drinking purposes, many employees preferred it because of its coolness. The canal water was often contaminated by discharge from the mills' water-closets.
3) Belvidere reservoir. This water was pumped from the canals and used by the corporations for fire purposes.
4) Well water.
5) Spring water. This was brought into the city and sold in carboys (large bottles in protective baskets or crates).
The Board went on record as saying that the cause of the epidemic was unknown at that time (end of 1890) but offered several theories.
1) Canals. It was now evident that the canals were being infected by discharge from Lowell Hospital, even though the waste was disinfected according to approved methods.
2) City water. Up to now, the city's water and health boards believed their water supply was safe, even though it was drawn from the Merrimack. A commonly held belief at the time was that running water purified itself, even though sewage was dumped into the river. The Board stated that this may have been the cause of the epidemic but did not know why it continued into late December (actually into March of 1891). They felt the disease was still present in Lowell at the end of 1890 and that the epidemic in Lowell had caused a serious epidemic in Lawrence, further down the river.