I'm a great believer in PEG ratio, but even if you think as I do that current Brazilian protests will have zero effect on the long-term growth rate of a partly-State-owned utility company, take those PEG estimates with a huge grain of salt. I don't think the earnings growth rate estimates are from anyone who understands much about the company. Now the estimates are 11.5%/yr, but when I first researched SBS they were as I recall 3%, which almost kept me from buying the stock until I convinced myself that the estimate was just idiocy.
My earnings growth rate estimate was and is:
Real growth = the long-term annual growth in water and sewer connections (which I put at 2.5% based on the last conference call) plus the long-term per-capita water usage growth (which I guess is maybe 1%)
Nominal growth = Real growth plus annual average inflation minus average annual depreciation in the Brazilian Real.