This image shows how rising damp effects a wall

Rising Damp is the name given to a form of dampness, which only comes from groundwater, moving up through interlinked masonry pour structures via capillarity.  There must be a suitable source of groundwater at the base of a wall and the absence of a Damp Proof Course.  Also, the rate of wall surface evaporation limits its hight.

When water is rising up a wall by capillarity, it creates a small electrical potential and negative ions travel from the positive ground through to the negative wall. The electro-osmosis system reverses the effect.

Note: If you see a black speckled mould growth rising from your wall floor level, its unlikely to be true rising damp and more likely atmospheric moisture due to the effect of contaminants carried by other water sources can have on moulds.

At the time of building rising damp is controlled by installing a physical barrier to moisture called a Damp Proof Course normally 150mm above ground level. In Edinburgh, I have seen DPC installed in building constructed from 1830.

Where there is no DPC, or it has been bridged or broken down then, the following remedial rising damp control measures are used:

Install a remedial chemical damp proof course to control the groundwater by controlling capillarity movement by fluid injected under pressure or cream injected into the mortar joints.

Install a remedial electro-osmotic system to control the rising groundwater by reversing its flow. This is a fully reversible damp proofing system. Also, the materials can be recycled at the end of the buildings life.

Cut into the walls and install a physical damp proof course, but this could affect the building structure.

Drain the ground around the property. This may not be practical and needs to be monitored