Pick the crop, the source water, what the system has to answer and what treatment is in the room. It returns the sample points, the instrument package, where the drain can go, what Ontario checks — and what the water is worth to you.
Reuse first. Discharge last. Every litre of drain was paid for twice — once as water, once as the fertiliser in it. The package exists to send back every litre that can safely come back, prove the treatment that makes that safe, and put a dollar figure on it.
verified read from the cited sourcederived calculated from cited figuresdefault starting point — replace with site data
Step one
The site
The loop
Sample points
The package
Instruments
Instrument
Where
Speed
Why it is in the package
One multi-ion analyser sequenced across points by motorised valve costs less than two analysers and reads the same. That is the correct saving. Dropping the analyser is not.
The first sodium lever
Source water and blending
Blend check
Fresh water brings its own sodium. The saltier the source, the more of it a blend needs — and the less a blend can do.
mmol/L
mmol/L
Rain from the roof
Rainwater is the lowest-sodium source there is. What a roof can collect against what the crop uses:
ha
collection roof
mm
verified · Windsor 1990–2020 normal
%
default · first flush, overflow, evaporation
m³/ha/yr
verified · Wageningen, ~1,000 L/m²/yr
The one place it touches the water
Where the drain goes
1 · reuseAs isChemistry under the ceilings, treatment verified.
2 · reuseBlendSodium or chloride climbing. Fresh-water share set from the ion readings, not a spring percentage.
3 · reuseTreatDisinfect for biology. Acid for bicarbonate. Remove sodium when blending cannot keep up.
4 · waitHoldWrong but not yet identified. Not the clean tank, not discharge.
5 · last resortDischargeNothing above can bring it under the ceiling. To a field, the sewer, a hauler or on-site treatment — logged with why.
Fail-safe position
Every diversion is a record
Position, reason, the reading that justified it, the volume through the meter — and for a discharge, where it went and why reuse was not possible. Treatment reject water and backwash are discharges too and are logged the same way.
The question everybody asks
What actually sends water to waste
Biology is never a dump decision. Chemistry rarely is. Bacteria, fungi, oomycetes and viruses are a treatment problem — fix the treatment, do not empty the tank. Sodium and chloride are blended down first and, where a desalter is fitted, taken out. Bicarbonate is neutralised with acid. Boron is the ion most likely to force a discharge, because most treatment removes little of it.
Signal
What it actually means
Action
Verifying the treatment train
How you handle a virus you cannot see
You do not detect it. You guarantee the treatment that stops it. On a UV that is delivered dose — transmittance, flow and lamp hours against the 250 mJ/cm² drain-water standard. On ultrafiltration it is membrane integrity — a daily integrity test demonstrating at least log 4 removal. Prove either continuously and tobamoviruses do not pass, whether or not anything ever measured one.
What the system computes, not senses
The sensing is bought. This is the part that is yours.
Ontario
What the regulator actually checks
Phosphorus, not sodium. Greenhouse fines in Essex County have been for phosphorus in stormwater ponds and for greenhouse water reaching drains and catch basins. The ion panel does not measure phosphate, so a compliance record needs it added.
Stormwater and approvals
0.5 mg/L total phosphorus in the stormwater pond — the limit written into greenhouse approvals cited in recent fines; samples of 9.1 and 19.6 mg/L were prosecuted. verified
0.03 mg/L — Ontario's interim water quality objective for phosphorus in streams. Above 1.0 mg/L in a creek points at greenhouse water. verified
Greenhouse pond discharges sampled by the Ministry averaged 42.2 mg/L phosphorus and 91.9 mg/L nitrate, against 0.095 mg/L in a clean stormwater pond. verified
An Environmental Compliance Approval is needed above 10,000 L/day discharged; a Permit to Take Water above 50,000 L/day taken. verified
Nitrate warning 10 mg/L NO₃-N and suspended solids 25 mg/L at the pond outlet — no published greenhouse limit; these follow drinking-water and typical approval values. default
Pond outlet sampled monthly for phosphorus, nitrate and solids, with conductivity logged continuously. default
Nutrient feedwater to land — O. Reg. 300/14
No more than 130 m³/ha in 24 hours; up to 250 m³/ha from May 16 to September 30 where the conditions in s.39 are met. verified
Restricted period December 1 – March 31; never on frozen or snow-covered soil. verified
Setbacks: 20 m from the top of bank of surface water · 100 m from a municipal well · 15 m from a deep cased drilled well · 30 m from any other well. verified
5 nutrient units or more generated needs a full nutrient feedwater strategy. One unit is the lower of 43 kg N or 55 kg P₂O₅. verified
Lab analysis for N, P, K, regulated metals, boron and sodium before the first application; application records within 30 days; annual update by February 15; records kept 5 years. verified
Sewer
Kingsville (Ruthven) accepts greenhouse process water under its greenhouse sanitary sewer by-law at $3.07/m³ metered, off-peak pumping expected. verified
Sanitary sewer limits, using Windsor's by-law as the regional reference: phosphorus 30 mg/L · TKN 100 · BOD 400 · suspended solids 500. Storm sewer phosphorus 1.0 mg/L. derived — confirm against the local by-law.
What the water is worth
Cost Calculator
Every field starts at a default with its source under it. Water, sewer and fertiliser prices are the grower's — type over any of them and that figure is kept, marked as yours, whatever municipality, route or treatment is chosen after; reset returns the default. Other fields follow the selectors until edited. On a running site the volumes come from the meters and the fertiliser value from the measured drain.
Your prices — set by the grower, kept when anything else changes
$/m³
$/m³
$/kg
$/kg
$/kg
$/kg
$/m³
Site and treatment
$/m³
ha
m³/ha/wk
weeks
% of treated
%
%
Against dumping every litre
—
saved per week
Crop profile
Profile
Thresholds
Water-borne pathogens of concern
Say this out loud before you quote it
What this package cannot do
No continuous virus detection exists
Flow cytometry counts bacterial cells. Viruses are an order of magnitude too small to appear, and oomycete zoospores are not reliably counted either. Anything marked no live method above is handled by proving the treatment — dose on a UV, integrity on a membrane — by hygiene and by plant inspection. Never by dumping the tank.
What it does instead
▸Proves the treatment is working, continuously, instead of finding out when a crop fails.
▸Sends back every litre that can safely be reused, and prices what that saved.
▸Keeps the phosphorus record Ontario approvals are actually enforced on.
▸Says the day the water changed against this site's own baseline, and aims the lab at it.
▸Logs every discharge with its reading, its destination and why reuse was not possible.