Features and types of drainage systems: indoor and outdoor

Is your basement constantly damp, with high humidity and mould? In this situation, it is worth considering making basement water drainage for proper waterproofing of the room. You should pay attention to this problem because a damp and wet basement can create a lot of inconvenience. That is where fungus and mould can spread throughout the house, which is very bad. In any home, the basement can leak, so it’s worth taking care of proper drainage beforehand.

Use our article to find the best basement drainage system depending on your preferences and the features of your home. 

Interior Vs. exterior drainage systems: a breakdown by parameters

Drainage in the basement can be carried out with internal or external systems. Each of them has its features, advantages and disadvantages. We propose to consider them depending on several parameters.

Difficulty of installation

The external drainage system for the basement is mounted on the perimeter of the entire house, so contractors will have to dig a trench around the foundation with an excavator. Before this work is done, you must remove any excess vegetation on the site and other obstructions to the excavation. After the trench is excavated, all the soil will be placed around the house’s foundation. Then the system is installed, and the soil is backfilled. After that, the landscaping will have to be redesigned, and everything will be back in place.

An interior basement drainage system has no such disadvantage. It can be installed in just 1-2 days, and you have to go over the floor with a jackhammer to place the drainage system on the knocked-out clean stone. Real professionals can complete everything with a minimum amount of dust. Once the pipes are laid, they are appropriately cemented so the system is completely hidden from view. At the same time, the landscape and foundation remain entirely intact. 


Outdoor cavity drainage system basement waterproofing loses out on this issue. If the house is not on a slope and there is enough space between your building and the neighbour’s to dig a gravity drain, the system will not have a regular opportunity to drain the collected water to drain it down the slope. The system will only work correctly if the water drains down naturally. If you connect the drain to a storm drain or create a dry well, you will also have problems in this situation – the system needs to be installed much lower in level from the drain outlet line. At the same time, it is worth calculating the collection tank clearly for the volume of water discharged. In some situations, you can add a drain pump.

Maintenance Costs

An external system is quite expensive and requires special maintenance. This system is already provided in your home and was installed during construction. If it wasn’t, it’s worth worrying about a new one. In any case, it requires special maintenance. In this situation, excavation work is also required again. This system is prone to frequent clogging. Quite often, when the outdoor system completely fails, it must be replaced with a new one. As for the price, it will cost much more than the internal one – about two times. 

Inside basement drainage systems can boast excellent economics and low operating costs. The installation of this system is not so destructive, and the soil can be restored after backfilling, so there is no need to spend money on excavation work and pay more landscapers. The system is also much easier to maintain. This system is excellent for long-term or short-term solutions, and its installation cost is 50% cheaper than external drainage. In addition, indoor systems are much more affordable to maintain and have a much longer lifespan.

Exterior basement drainage systems

The exterior basement drainage system is effective when you want to block all water sources in the house – gutter extensions, clogged gutters and leaks due to heavy rainfall. Exterior basement drainage works on the principle of the French system – it allows you to redirect groundwater even before it gets close to the structure’s foundation. The basement exterior drainage system protects the basement walls from collapse.

Mounting exterior drainage plates is done at a relatively shallow depth to effectively prevent the penetration of rainwater and other precipitation to the basement wall. In this situation, mounted special perforated pipes with a coating of gravel – special drains. But this system also has specific pros and cons.


The presented drainage of the basement allows for minimizing the hydrostatic pressure of groundwater on the foundation. As a result, you can put an external waterproofing membrane, which is quite effective when laying a stone foundation. While installing this system, you can continue to operate the basement. 


The only disadvantage is that an exterior house basement drainage system requires excavation work to install the drain, which can be messy and cost a pretty penny. In this situation, a perimeter trench is dug around the entire house. The exterior can be significantly ruined during installation, and landscaping will need to be done again.

Interior drainage tile systems

Interior basement water drainage systems involve the installation of perforated pipes around the perimeter of the floor inside the foundation and along the floor, which will direct water to the drainage pump for efficient drainage. Flushed gravel is placed around these pipes and is also covered with a layer of filter paper. 


Interior basement drainage enables efficient drainage of rising groundwater, minimizing external hydrostatic pressure and preventing deterioration of concrete walls. No additional hydrostatic solutions are needed during the installation of this system, as well as no excavation work. Your landscaping around the house will remain completely intact. Install interior basement drainage channel can be installed at any time of the year. In addition, an undoubted advantage is lower cost compared to an external drainage system.


This basement cavity drainage system is not appropriate for a ready-made room since, during the installation, some layers of concrete will have to be removed. During the works, the basement will be entirely closed for use. In addition, the option presented is not suitable for a stone or brick foundation of the house. If you do not install an exterior sealant, stone masonry can also leak water.