Choice of lining for a well (PVC or HDPE)

[joshea]

About to decide on a contractor to have a well bored for our new house.

Just wondering if anyone has advise on the choice of lining for a well

The options from the different contractors are,

1. High Density Polyethylene
2. PVC

Any other advise on same also welcome

 

[ajapale]

Casing Material
Water well casing may be constructed of steel or plastic (of various types). Permanent steel casing is not
advised as it may corrode in certain groundwaters and also encourage the development of biofilm slimes.
The driller should certify that the casing is suitable for the specific borehole. Factors that affect casing selection
include: cost, diameter, drilling method, water quality, strength requirements, and corrosion resistance. The
joints between lengths of casing must be watertight.
• Steel casing used in water wells should conform to the standards of the American Society for Testing
and Materials (ASTM), British Standards Institute (BSI) or American Petroleum Institute (API).
• Plastic casing may be of several types: Polyvinyl chloride (PVC), Acrylonitrile butadiene styrene (ABS),
rubber-modified polystyrene (SR), High Density PolyEthylene (HDPE), polyolefin, polypropylene, and
Glass-reinforced plastic (GRP or ‘glass fibre’).
• Plastic casing must have sufficient strength to withstand the pressure and setting temperature of the
cement grout that will be placed in the annulus outside the casing. Well casing should be specifically
designed for that purpose. Cheaper but weaker types of pipe, such as sewer pipe, should not be used.
Casing Depth
Casing should be installed to sufficient depth to fulfil the three functions listed above.
Where the aquifer is unstable, e.g. sands or gravels, the casing and well screen (see below) should normally
be installed to the full depth of the well.
• In rock, casing should be installed and grouted to a minimum depth of 20 metres below ground, or to 10
metres into bedrock, whichever is the greater.
• Casing should also be installed to at least 2 metres below the depth at which the pump will be set. This
will ensure that (a) the pump and rising main are protected from any collapse in the well, and (b) the
pump is set a good distance above any muddy sediment in the bottom of the well.

The extract above comes from the IGI: Institute of Geologists of Ireland. Guidelines.pdf (application/pdf Object)


You should contact three or more reputable well drillers who operate in your area and get them to quote for boring the well. Ask them to give the names of satisfied customers in the locality and check with them as to the quality of the work ect.


At present well drilling costs in the order of €3k (more if there is a deeper well or there are problematic ground conditions) the sub pump and pressure set and controls should cost in the order of €1k. Most wells in the west / south west of Ireland will require some form of filtration to remove Iron/Manganese, correct pH, etc. If your water is particularily bad then it could cost about €2k to put in the appropriate water treatment.

Drillers in the South and West of the country use the blue uPVC liners (not sewer pipe) and sometimes cut slots in the liner to allow the water through. In general wells in this area are only grouted in exceptional circumstances.

Be sure to seal the well head correctly and include a vermin proof well cap.

If your house is over 7 years old and if there is no mains water in the locality you may quality for an individual well grant from the local authority.

Drillers are listed in the Golden Pages but TJ Cross (Abbeyfeale), Munster Drilling (Kanturk) and Lenihans (Glin) are three very highly regarded drillers in the SW.