Madison water and health officials said Thursday the news from manganese sampling in the most seriously affected neighborhoods continues to be encouraging.

So far, the Madison Water Utility has collected and tested for manganese about 550 household samples from hose taps outside homes and businesses in the three areas where wells have shown to be producing high levels of the problem mineral. That testing showed:

94 percent of all samples were below the aesthetic standard for drinking water of 50 parts per billion, set by the federal Environmental Protection Agency.

6 percent of the samples were between the aesthetic standard of 50 ppb and the lifetime health advisory level of 300 ppb.

Only four of the samples were above the EPA lifetime health advisory level of 300 ppb. All of those were retested and found to be below the aesthetic standard of 50 ppb.

The 559 completed tests represent about 40 percent of the number of households expected to be sampled in the neighborhoods with wells that produce high levels of manganese. Those wells include No. 3 on the East Side of the Isthmus, No. 10 on the West Side in the Nakoma area and No. 29 on the Far East Side.

The test results show the current level of manganese in neighborhoods where the mineral has been a problem. Utility officials plan to compare results to levels after crews finish flushing water mains in the area with high-speed water.

Dr. Thomas Schlenker, director of the Madison-Dane County Health Department, said Thursday he intends to leave a drinking water health advisory for the affected areas in place until testing is completed. The advisory would be lifted first for those in the well No. 3 area, perhaps as soon as within two weeks, because flushing is almost complete in those neighborhoods.

Under the health alert, people with liver disease and infants up to 6 months old are advised not to drink water from their taps because the high- velocity flushing could temporarily elevate manganese in some areas to levels beyond the EPA's recommended health standards.

In the well No. 3 area, 147 of 163 samples were below 50 parts per billion. Fifteen of the 163 samples were between 50 ppb and 300 ppb. One spigot at an area business was found to be above 300 ppb for manganese but was retested four times and each of those tests was below 50 ppb.

David Denig-Chakroff, general manager for the Madison Water Utility, said well No. 3 is now being used only during the day when pipes are being flushed. It is likely the well will be placed on standby after flushing is complete and used only seasonally, he added.

Of 209 samples taken before flushing started in the well No. 10 area near Nakoma, 197 were below 50 ppb and 11 samples were between 50 and 300 ppb. One tap that tested above 300 ppb was tested three more times and showed levels of 3 ppb, 57 ppb, and 11 ppb.

In the area of well No. 29, the well that had the highest levels of manganese and is currently not in use, 147 of 154 samples taken so far were below 50 ppb. Five of the samples were between 50 ppb and 300 ppb. Two samples were above 300 ppb and are being retested.

One very discolored sample tested initially at 10,100 ppb. But the water cleared quickly when allowed to run and the sample tested a second time at 64 ppb.