Identification

• Alkalinity of water refers to the amount of base present, either naturally or acquired from submersed materials. These bases are known as bicarbonates, carbonates, phosphates and hydroxides and raise the water pH to above 7.0.
  
  

Sources

• Depending on the types of bedrock or soil in a region, groundwater may naturally have an alkaline, neutral or acidic pH. In man-made water features added to a garden, the construction materials may contain salt residues that, when in contact with water, change the water's pH. Concrete is known to make water alkaline, as do fish excrement nitrates.
  
  

Significance

• Backyard water features used merely for decorative effect can house any water pH range. However, if the features are to support plant or fish life, alkaline water conditions can cause fish to die or plants to grow poorly. Tolerance to alkaline water environments varies by plant or fish species.
  
  

Prevention/Solution

• Concrete or stone water features coated in non-toxic sealants can alleviate issues of alkalinity. Chemicals from pet stores, often used in aquariums, may also be used to manipulate water pH in ponds and fountains.