No thumb rule for either of the things. That depends upon the type of product and production capacity. Utility cost has many factors to consider. For example, here in India, WFI is costing Rs0.75/liter, compressed air Rs 0.3 for cu.ft and steam Rs 0.5 per kg.
Typical analysis for WFI
1. Cost of purified water
2. Cost of steam
3. Cost of electricity
4. Man power cost
5. Cooling water/ chilled water cost
6. Initial investment spanned over life of the equipment (or upto the depreciation period)
7. Cost of maintenance
Typical analysis for compressed air
1. Cost of electricity
2. Cost of Cooling water
3. Cost of man power
4. Initial investment
5. Cost of maintenance
Typical analysis for steam
1. Cost of fuel
2. Cost of feed water
3. Cost of man power
4. Initial investment including fuel storage
5. Cost of maintenance