If you're at the point of the game where you have the Pride of the City Challenges, then you've triggered an event called H2 Oh No, which reduces your Yield.  Read on for the text that is displayed on the start of the event, and a hint on what to do next.

H2 Oh No
While working on some paperwork for the business, you notice an official-looking black sedan park outside the brewery.

In walks a suited figure, seeking your attention.

"Are you the owner and operator of (your brewery)? Yes, well, I'm with the city and I'm afraid I have some bad news.

"As you know, the water main for the purification facility in this area of downtown sources directly from the lake. Just this morning, our pressure monitoring system began reporting an anomaly at that location.

"It seems like something may be clogging the main intake pipe, and until we fix that, this city block will be experiencing lower than normal water output."

You ask (one of your employees) what that means for your brewing capabilities.

"Well boss, with such a largely reduced amount of water, it looks like we're going to have to reduce the Yield of every Batch by 50% until the blockage is fixed."

You ask the city official how long the fix will take.

"We're working on it right away.

"My office has requested a work order form from the Office of Forms and Red Tape, and as soon as we receive that, we'll file the form with the Office of Work Order Organization, which will then forward that to the proper Work Order Adjudication authority.

"Once we hear back that the work order is approved, we'll request and file a form with the Office of Work Order Scheduling, which will then hire about 12 guys to do the work of 4 guys removing the blockage.

"All in all, I'd say it'll take about four years, give or take a few months of course -- sometimes there's a typo on a form and then you have to start all over."

It's going to be very difficult to beat Blau or even remain profitable with only 50% Yield capability. You ask if there is anything else you can do.

"Not unless you know someone with their own boat willing to fish out the obstruction themselves."

Better keep your eyes out for someone with a boat.

To get past the H2 Oh No event, you need to either finish Pride of the City Challenge #3 or #4, then you'll get an event that you can finish to fix the water main.  So just complete one of those 2 challenges, and shortly after (in a few months) you'll get some help through an event called "Hunt for the Great White Ale".