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Well Water Safety

Types of Wells

To effectively maintain your well, it is important to understand:

  • Type of well you have
  • General construction principles of your well system
  • Potential vulnerabilities of contamination depending on type of well

Drilled Well
Drilled Well

Dug Well
Dug/Bored Well

Jetter Well
Driven, Jetted,
Sand Point Well

Comparison of Well Types

Well Type

Drilled Wells

Large-Diameter Wells

Well Points
(Driven, Jetted, Sand)




Drilled with rotary or cable-tool water well drill

Shallow or deep (15m/50ft to 60m/200ft or more)

Small-diameter casing, 10 – 20 cm (4 to 8 in.)

Made of steel (usually)

Dug by backhoe or by hand

Usually shallow (9m/30 ft or less)

Constructed with boring machine

Shallow or deep (15m/50ft or less)

Driven in or jetted with water

Shallow (15m/50ft or less)

Large-diameter casing (60cm/24 in. to 120cm/48 in.)

Made of concrete, rocks, bricks, or wood

Small-diameter casing (2.5cm/1 in. to 5cm/2 in.)


Can reach deeper aquifers

Can drill into bedrock

Less subject to contamination, especially if deep

Easier to seal

More constant temperature

Easy to construct

Inexpensive initial cost

More controlled hole than dug well

Generally simple and inexpensive to install


Large casing provides storage

May be used in poor-yielding aquifer


Vulnerable to deep aquifer contaminants

Poorer natural water quality from some deep aquifers may occur, e.g., from salt

If shallow, water shortages are possible in dry periods

Easy to seal properly, but requires large volumes of material

Vulnerable to near-surface contamination

Water temperature may change seasonally

Limited to permeable materials

Shallow water table

Limited yield and possible shortages in dry periods

Vulnerable to near-surface contamination