A drain field needs to be properly looked after in order to function and to take care of the sewage your home produces. A large issue with drain fields is overflowing because of rainwater. If a drain field overflows due to an abnormal amount of added rainwater, the process of purifying the sewage water can be affected. This renders the drain field less functional, and it can take time before it is back to normal. In order to avoid an issue like this, you need to control heavy runoff water and make sure it's not going to your drain field. In order to do so, there are a few things you should think about regarding rainwater control.
The first thing you need to do is to make sure the runoff water from your house is prevented from reaching your sewage system. Rainwater that is gathered in your gutters can reach quite large volumes, as all rain that falls on your roof is redirected there. An easy way to gather rainwater from your gutters is to put a rainwater cistern below your gutter's drainpipe. This allows you to collect the rainwater to then dispose of it wherever you please. You could start off with an ordinary barrel to get an estimate on how large your cistern should be, as you'll notice how quickly the barrel fills up.
Another way to prevent large quantities of rainwater to reach your drain field is to have a rain garden put between any slopes and the drain field. Rain gardens are excavations filled with absorbing soil and mulch to collect the rainwater and allow it to reach the groundwater as soon as possible. Plants can be grown on the rain garden for an aesthetic appeal. It's also good if you have a bore on your property, as a rain garden will add to the groundwater supply quicker than rainwater falling on untouched soil would.
If neither of these methods do any good because of the placement or conditions of your drain field, you need to consider expanding the drain field itself to be able to accept larger quantities of water without disturbing the purifying process. Have a professional evaluate how much larger it needs to be to accept the average amount of rainwater that is added to it. You also need to remember to update your pipes. If you expand your drain field a lot, you'll need to considerheavy duty drainage systems to replace the system you have. Remember that you might also need to update the size of your septic tank to match the capacity of the drain field.