Metal gutters can prevent a multitude of drainage problems around your home, from soil erosion to basement leaks, and serious structural problems caused by water damage. A common problem that keeps gutters from working properly is the lack of a slope.
Check the Slope
Using a level, you can check to make sure your gutters slope. They should slope downward toward the downspout to allow water to flow out freely. Water that doesn't run out properly and instead collects in metal gutters can cause corrosion which leads to small leaks.
There's no hard rule on the angle of the slope. As long as there is enough slope the water will naturally run out. A good guideline is that the pitch should cause a decrease somewhere between 1 to 2 inches over a 40-foot run. Measure from the roof edge at both ends of the gutter if you want to be sure.
Adjust the Hangers
If your gutters don't slope, then you only need to adjust the hangers and lower them slightly where necessary to achieve the correct slope. You can unscrew them or use a pry bar to remove the fastener holding the hanger in place, lower it the correct amount, and refasten. This simple act can turn problem gutters into an efficient drainage system.