Sometimes people confuse the gutters and the downspouts. Although they are all part of a water system for homes they are not the same thing.
For example, gutters are what run horizontally or parallel from the ground and downspouts run vertically from the gutter to the ground or roof.
It is basically the tunnel or tube that transports the water from the gutter to the ground.
Although a downspout can be clogged at any part of the vertical section, there are areas that are more common to clog than others.
One fo the most common is the first or second elbow directly connected to the gutter. In fact, it is the most common area of the downspout to get clogged. There are many reasons for these clogs to happen in the elbows.
1: The elbow is pinched too tight.
2: The elbow is the wrong size
3: The elbow is installed incorrectly
4: There is wiring running through the elbow
5: There isn't a downspout filter installed
6: The gutters have not been cleaned for a really long time and have allowed a lot of build up to slowly clog the elbows
Honestly, these areas are far less likely to clog. If they are clogged, it is usually because an area below it (often an elbow) is clogged and the debris has just backed up to the straight vertical section. Sometimes these areas can clog without a clog lower. When this happens it is usually caused by tennis balls. Other than tennis balls there might be Christmas light hangers. Not much else will clog a vertical section that isn't also clogged below it.
Some downspouts do more than just go straight down to the ground. Oftentimes they curve or bend around trim, exterior rooms, decks, additions, etc. When this happens it creates another area that is highly likely to collect debris and completely clog.
After the straight vertical section has come all the way to the ground it often turns with an elbow to direct the water away from the house. These sections are yet another place of common clogs for downspouts.
Underground drains do get clogged. Often times it is because debris has come down the downspout for so many years that it has built up enough to clog the underground drain pipe. Other times it is because some sort of root system has penetrated the underground drain and is now blocking debris from exiting the pipe.
It is simple. Almost 99% of downspouts can be cleaned or cleared by sucking from the top with our Gutter Vacuum System and blowing from the bottom with heavy duty backpack blowers.
Some downspouts require more work. More work often means taking apart the downspout by drilling out rivets or removing screens and then by hand or auger or vacuum getting the debris out.
Believe it or not there are some downspouts that need replaced entirely in order to get the gutter system to flow again.
When the bottom of downspouts are connected to underground drains this might mean that it is impossible to blow from the bottom without either a) struggling to disconnect the drain from the downspout b) taking apart the downspout in order to get it disconnected from the underground drain.