SimCity Strategy Guides
Your Sims generate a lot of digital poo which all has to go somewhere. Fortunately SimCity does have options which are slightly more civilized than flinging it out the upstairs window onto a passing donkey.
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A common complaint in SimCity's management is that sewage pipes are backed up or over-capacity and yet the capacity reports as being adequate.
This occurs because of the way sewage is handled and reported. Unlike water or power, sewage does not 'flow' uniformly (it's best not to give this too much thought whilst you're eating your lunch). Because output of sewage and capacity is measured in k/gal (that's 1000 gallons) per hour, any peaks in incoming sewage which are greater than the capacity will cause blocked pipes but won't necessarily affect the average typical flow of sewage your city experiences on an hourly basis - which is what is reported on the sewage panel. Essentially you are looking at an 'averaged' summary value for the hour, but what happens on a minute-by-minute basis within that hour can vary considerably.
Example: Your city reports needing 60k/gal per hour of sewage processing. You have 90k/gal per hour available from your sewage treatment plant, 90 is more than 60 so that ought to be Ok, so why isn't it?
60k/gal of sewage per hour is obviously 1k/gal of sewage per minute, but because sewage doesn't flow uniformly, the 60k/gal might well come into the sewage treatment plant at the rate of 0.5k/gal per minute for 10 minutes, but then suddenly jump to 5k/gal per minute for the next 2 minutes before falling again.
Your treatment capacity of 90k/gal per hour is equal to 1.5k/gal a minute. Obviously 5k/gal per minute is too much for a capacity of only 1.5k/gal per minute, and yet the hourly and daily capacity seems to be enough.
Obviously you can increase capacity by placing more tanks at an existing sewage treatment plant, or by building another plant if your existing ones are full, however this isn't always necessary.
Quite often it's only a very small hiccup in sewage flow which corrects itself shortly, so rather than possibly over-reacting and spending a lot of money unnecessarily, check your pollution data map to see if you have a sewage problem. If sewage isn't affecting your Sims, then the problem is not that severe and can probably be ignored until your city grows.
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It is worth noting that I don't actually have this achievement because although it is easy in theory, in practice it is remarkably straightforward to consistently fail because of the way the game handles sewage (ew...).
With 10,000 or more residents, prevent sewage issues using only Sewage Outlet Pipes
Two sewage outlet pipes should be more than sufficient to cover a small city of 10,000 or so Sims, however it is easy to consistently fail this achievement due to the lack of consistency of sewage management.
The worker's curry night at the Petroleum HQ proves to be too much for this sewage treatment station
If you put both outlet pipes side-by-side on the same road, because sewage flows along the road, it meets the first outlet pipe and stops, backing up and causing a problem and thereby failing the achievement.
If you place the pipes on separate roads then in theory the sewage will be split, travelling in two directions and not exceeding the capacity of either pipe. In practice the game doesn't seem to handle this very well and it will divide up the flow poorly, creating the same problem of intermittent treatment happens at each outlet.
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