All of these are listed as making mineral water(s) in Dublin City, while they are a good bit later (1918 street directory) than you would have hoped, at least they give you something to start researching:
- Bewley & Draper Limited, 23 Mary Street;
- Brights, Walter Ltd. (successors to J. Shanks and Co. Ltd.), 55-56 Townsend Street;
- Cantrell and Cochrane Ltd., 2-12 Nassau Place;
- Egan, John & Son, 30 Ormond Quay Lower and 23-24 Great Strand Street;
- Hamilton, Long & Co. Ltd., 107 Grafton Street and 3 Sackville Street Lower;
- Hovenden & Orr Ltd., 4 Glover's Alley and 131 St. Stephen's Green South;
- Irish Direct Trading Co. Ltd., 8-19 Glover's Alley (poss. connected to H & O Ltd., given the address?);
- Kernan and Co., 68 Camden Row;
- Manchester Chemical Co., 14a Hawkins Street;
- O'Brien & Co., 5-9, 11-13, and 17-18 Henry Place;
- Taylor & Son Ltd., 17-23 Foley Street;
- Thwaites, A & R & Co. Lim., 57 Sackville Street Upper;
- Twinem Bros, 31 Clanbrassil Street Lower and 66a Circular Road South.
Edited to add: A quick check of the Freeman's Journal around 1897 confirms that Bewley & Draper, Cantrell and Cochrane, Hovenden & Orr, and Thwaites were on the go (not to say the rest weren't).
Another company I noticed in the Journal not previously mentioned is the Dublin Artesian Mineral Water Co. Ltd.
