Sold by the metre, but the quote is written by geology

The well is the building work with the most honest unknown: it is paid by the metre, but nobody knows for sure how many metres it will take until the rig reaches water. Between the list price per metre and the final bill sit two forces the flyer does not show: geology — hard rock, cave-ins demanding double casing — and the fixed equipment: submersible pump, wellhead, electrical connection and permits, which cost the same above a 30-metre hole and above a 250-metre one. This calculator breaks the quote into its three items and sums it up in two honest numbers: the effective metre — total divided by depth — and the index ι, how many times the total exceeds the metres-only bill.

The formula: metres, geology and equipment

The model is the classic decomposition of the vertical worksite. The metres bill is D·c: the estimated depth times the cost per metre of drilling and casing. On that bill acts the geological surcharge g: zero in cooperative sediments, above 40% when the rig meets hard rock or collapsing layers. Outside the product stays the equipment E — the fixed cost disguised as an accessory, like the fence's gate. The index ι = C/(D·c) is dimensionless and works in any currency: it says at once whether you are buying metres of drilling (low ι) or an installation with a hole under it (high ι).

The scale of the depth: the equipment dominates the short well

The table sends the rig down with everything else held equal (90 per metre, geology 20%, equipment 3,250):

On the 30-metre well half the price is equipment: the effective metre is two and a half times the list, and the quote describes a pump with a hole under it. On the deep well the equipment disappears into the bill and the effective metre slides towards the list. It is the same rig, but two purchases of opposite nature — and the list-price-per-metre comparison does not tell it.

A complete numerical example

Typical well: 80 metres estimated from nearby wells, 90 per metre drilled and cased, geological surcharge declared at 20% — some compact banks expected — and a complete 3,250 installation with submersible pump, wellhead, panel and permits. The metres bill is 80 × 90 = 7,200; geology brings it to 8,640; the equipment closes at 11,890. The index is 11,890 / 7,200 = 1.65: the effective metre is 149 — not the list's 90 — and the equipment weighs 27.3%. Whoever compares two quotes «at 85 and 95 per metre» without reading geology and equipment is comparing the wrong item.

How to read the quote index

The four bands tell four worksites. Below 1.3 the quote is in line: cooperative ground, equipment in proportion — the territory of deep wells in known sediments. Between 1.3 and 1.6 the inflation is contained: the physiology of the well-quoted well. Between 1.6 and 2 geology and equipment make themselves felt: it is the territory of the preliminary survey and of the interrogated neighbouring wells. Above 2 the hole is only the beginning: the metres bill doubles along the way — typical of the short well with full equipment, or of commanding rock. No band is «wrong»: the index says where to point the lens before signing.

The depth: estimated from nearby wells, not by hunch

The commanding variable is also the least negotiable: the aquifer sits where it sits. But it is no mystery: nearby wells — the neighbourhood's, the regional drilling registers, the stratigraphies known to local firms — say with fair precision at what level water was found around you. The serious estimate starts there, and the serious contract completes it with the clause that counts most: the written price of the metre beyond the estimate, and what happens if the well turns out dry. The rig discovers the truth metre by metre: the contract must have foreseen it beforehand.

The geology: the item declared layer by layer

The surcharge g is the honest way to represent what the drilling meets. Sand and sediments drill fast but collapse: they demand immediate casing. Compact rock holds the walls but consumes tools and hours: the metre in granite can cost double the metre in clay. Mixed layers are the worst: tool changes, double casings, lost days. The local firm knows these layers by name — which is why the quote of whoever has already drilled within a kilometre is worth more than any teaser price: local geology is their competence, not their risk.

International perspective: feet, gallons and the same three items

The domestic well is universal, the conventions are not. North America prices by the foot (multiply by 3.28 for the metre) and measures yield in gallons per minute; Europe prices by the metre and measures in litres. Everywhere the bill has the same three items of this model — metres, geology, equipment — and everywhere the same two rules hold: the water found must be tested before drinking, and the well must be permitted before drilling, with local rules on distances from septic systems and boundaries. The calculator is parametric and currency-free precisely for this: depth, unit cost, geology and equipment are explicit inputs, and the index ι compares quotes from different markets on the same scale.

Limits of the model and correct use

The model photographs the standard domestic well: it does not cover prolonged yield tests, the softening and filtration the water analysis may impose, nor special artesian wells with pressure heads. The depth is estimated from data and verified with the contract; the equipment is specified item by item — pump, delivery pipe, panel, permits. And the well is often the beginning of a water chain: what comes out of the aquifer is almost always hard, and the water softener size calculator sizes the next step; for the connection trenches between well and house, the excavation cost calculator completes the estimate.

The scale of geology: the rock rewrites the quote

The surcharge g is the item that separates two quotes with the same rig. The table runs it over the base case (80 m at 90, equipment 3,250): every step is a different layer under the same lawn.

Between cooperative sand and full granite run 7,200 — eighty metres of drilling at list price — without the project changing by a metre: what changed is what lies underneath. That is why the serious quote declares the geology layer by layer, with prices for each: the «all inclusive» flat rate on unknown ground is almost always the dearer of the two — because the risk, someone pays it anyway.

The scale of the equipment: from the farm well to the complete home

The equipment E grows with the use, not with the depth. The table raises it on the base case (80 m at 90, geology 20% — drilling 8,640):

The 1,500 is the essential farm well — sturdy pump and simple head; the 3,250 is the home: panel, pressure tank, permits; the 8,000 is the complete installation with storage, first-pass filtration and automation — and here the equipment share brushes half the price. The right reading is by use: the equipment is sized on the water you need, the drilling on the aquifer that exists — two designs that meet in the same hole.

The effective metre: the number that compares quotes

The list says «90 per metre», but no well pays the list: it pays the total. The effective metre — total divided by depth, geology and equipment included — puts the quotes back on the same line: 149 in the base case, 216 on the short well where the equipment dominates, 121 on the deep one where it dilutes. It is also the number that unmasks the teaser price: the «75 per metre» that excludes the casing, the head cementing or the well development ends up, at the end of the job, above the «95 per metre» of whoever had written everything down. Totals are compared at equal specification, never the first line.

The well's yield: the litres count more than the metres

A well is not judged by its depth but by its yield: the litres per minute the aquifer grants steadily. The yield test — pumping for hours while measuring the level — is the act that turns the hole into a source: without it, you cannot size the pump nor know whether the summer irrigation will hold. The practical rules: the pump is chosen below the tested yield, never at the limit; the dynamic level decides the pump's installation depth; and the yield must be re-tested after years of service, because wells age — they scale up, they silt — and maintenance (purges, video inspections) is part of the life cost the initial quote does not show.

The well and its surroundings: the distances that decide the design

The drilling spot is not chosen by the aquifer alone: it is chosen by the mandatory distances — from septic tanks and leach fields (the strictest and most sensible rule), from property lines, from stables and fuel storage, often from roads. Every jurisdiction has its metres, but the logic is universal: the water you will drink travels underground, and what sits upstream of the flow arrives in your glass. That is why the serious survey looks at the site plan before the geology — and why the well «where there is room» is sometimes a well that cannot be permitted.

The contract: the five lines worth more than the price

The well quote is signed on the contract, not on the flyer. The lines that count: the estimated depth and the price of the metre beyond it — the queen clause; the casing specification — diameter, material, screened sections; the dry-hole clause — who pays what if the water is not there; the yield test included, with its duration written; the permits — who files them and who answers for the distances. The rig discovers the truth metre by metre: the contract serves to decide it beforehand, while it still costs ink and not diesel.

Frequently asked questions

How much does drilling a well cost?

With the decomposition C = D·c·(1+g/100) + E: the estimated metres times the cost per metre of drilling and casing, surcharged by geology, plus the fixed equipment. With 80 m at 90 per metre, geology at 20% and a 3,250 installation, the total is 11,890.

What is the well quote index?

It is the ratio ι = C/(D·c) between the total and the metres-only bill. Below 1.3 the quote is in line; between 1.6 and 2 geology and equipment weigh; above 2 the hole is only the beginning — typical of the short well, where half the price is the pump with its accessories.

How do you estimate the well depth?

From data, not by hunch: the neighbourhood wells, the regional drilling registers and the stratigraphies known to local firms say at what level water was found around you. The estimate is completed by the contract clause on the price of the metre beyond the estimate.

What does the cost per metre include?

Drilling and casing of a declared diameter: it is the item to read in the specification, because two «90 per metre» with different casings are not the same price. Head cementing, well development and the yield test must be verified item by item.

What does the fixed equipment include?

The submersible pump with its delivery pipe, the wellhead, the cable and electrical panel, the possible pressure tank and the permits. It is the disguised fixed cost: it costs the same above 30 metres and above 250 — which is why it dominates the short well.

Why does geology weigh so much?

Because the rig pays for what it crosses: sand collapses and demands immediate casing, compact rock consumes tools and hours, mixed layers impose tool changes and double casings. The metre in granite can cost double the metre in clay, at equal list price.

What happens if no water is found?

It is the risk to write into the contract before drilling: serious clauses provide a reduced price for the sterile hole or an agreed stop at a threshold depth. The «dry» well is not frequent where zone data are good — one more reason to estimate them well.

Do you need a permit for a well?

Almost everywhere yes, with local rules: declaration or concession for the use of the aquifer, minimum distances from septic systems, boundaries and other wells, and often the obligation to report the stratigraphy found. The paperwork sits in the model's fixed equipment and is verified before the rig.

Does the calculator work with prices per foot?

Yes, by converting: 1 metre = 3.28 feet, so a price per foot is multiplied by 3.28 to become per metre. The index ι does not change with the unit, because it is a ratio: just use depth and cost in the same family of units.

Can you drink well water right away?

No: first it is tested — bacteriology, nitrates, metals, hardness. Aquifer water is almost always hard and often ferrous: between the well and the house, filtration and a softener may be needed, a spending chapter of its own to budget together with the well.

When does a well beat the mains?

The count is made on the cubic metre: the well pays drilling, equipment and pump energy, the mains pays the tariff. With substantial irrigation or a distant connection the well often wins; for domestic use alone with mains available, the short well's high index already gives the answer.

What is NOT included in the calculated cost?

Prolonged yield tests, the water analysis and the treatments deriving from it (filters, softener), the connection trench between well and house, and site restorations. The model photographs drilling, casing and equipment: the rest is added item by item.

Updated July 2026