---

name: membrane-ro-fundamentals description: Reverse Osmosis (RO) and Electrodeionization (EDI) process fundamentals — formulas (recovery, rejection, NDP, osmotic pressure, TCF, NPF/NSP), authoritative standards reference (ASTM/ISO/USP/Ph.Eur./WHO/EN), vendor design windows (DuPont, Hydranautics, Toray, Suez, LANXESS), water chemistry, EDI quick reference, IT/EN glossary. Use when working on RO/EDI plant code, KPI calculations, or normative citations. user-invocable: false

RO & EDI Process Fundamentals

Reference for water-treatment expertise: formulas, normative standards, vendor design envelopes, water chemistry, and bilingual terminology.

Convention markers used throughout the membrane skills:

• ⚠️ — likely bug or incorrect numerical approximation in calling code; highest priority
• 💡 — enhancement opportunity (new KPI, new model field, refined threshold)

---

§1 — RO Process Fundamentals

All formulas in SI (LMH, bar, °C) with US field-unit (GFD, psi, °F) variant noted. Variables: Qf feed flow, Qp permeate, Qc concentrate, Cf/Cp/Cc concentrations, Am membrane area, T temperature.

1.1 Recovery (Water Recovery / Recupero)

Y = Qp / Qf

Typical ranges (vendor-dependent):

• SWRO single-pass: 35–50 %
• BWRO: 70–85 %
• BWRO high-recovery (w/ antiscalant): 90 %+
• Double-pass RO+RO overall: 70–80 %

Source: ASTM D6161-19; DuPont 45-D01504; Hydranautics TSB 107.

1.2 Concentration Factor (CF)

CF_ideal = 1 / (1 - Y)                          # for R = 1
CF_real  = (1 - Y·(1 - R)) / (1 - Y)            # for rejection R

At Y = 0.75 and R = 0.99: CF_ideal = 4.00, CF_real ≈ 3.97 (error < 1 %), so the ideal form is acceptable for SWRO/BWRO design.

Source: DuPont 45-D01591 (Design Equations).

1.3 Salt Rejection — three definitions

Variant	Symbol	Formula	When used
Observed (apparent)	R_obs	1 − Cp/Cf	What instruments measure
System (log-mean)	R_sys	1 − Cp / mean(Cf, Cc)	Standard reporting
Intrinsic (at wall)	R_int	1 − Cp / (β · mean(Cf, Cc))	Corrected for polarization

Concentration polarization factor:

β = Cwall / Cbulk = exp(0.7 · Y_element)

where Y_element is per-element recovery. FilmTec design limit: β ≤ 1.2 → Y_element ≤ 18 % (the 18 % per-element rule). Hydranautics is more conservative at 15 %.

⚠️ A code path that confuses R_obs with R_sys will under-report rejection by 5–15 % at high recovery. Always specify which definition the calculator returns.

Sources: DuPont 45-D01591; Hydranautics Terms and Equations of RO.

1.4 Permeate Flux (Jw)

Jw = A · NDP · TCF · FF                          # vendor model
Jw = Qp / Am                                     # operational

A = water permeability (LMH/bar), FF = fouling factor (0.85 design / 0.70 EOL).

Unit conversion: 1 GFD = 1.6987 LMH (≈ 1.70).

Typical design flux windows (vendor consensus):

Application	GFD	LMH
SWRO open intake (SDI 3–5)	7–9	12–15
SWRO beach well (SDI < 2)	8–10	14–17
BWRO well (SDI < 3)	14–18	24–30
BWRO surface (SDI 3–5)	10–14	17–24
RO permeate / 2nd pass	20–30	34–51

⚠️ A hard-coded flux_max = 25 LMH threshold is incorrect for SWRO (well above limit) and conservative for BWRO well (well below limit). Threshold must be water-source-aware.

Sources: DuPont 45-D01695 Rev 14 (Feb 2026); Hydranautics TSB 105; AMTA Optimum Flux Rates.

1.5 Salt Flux (Js)

Js = B · (mean(Cf,Cc) − Cp) ≈ B · mean(Cf,Cc)
Cp = Js / Jw                                     # key inverse relation

B is temperature-dependent but pressure-independent (unlike A). At cold feed temperature, Jw drops while Js is relatively unchanged → Cp rises → permeate quality degrades. Cold-water permeate TDS spikes are explained by this relation.

Source: DuPont 45-D01591; Hydranautics Terms and Equations.

1.6 Net Driving Pressure (NDP)

NDP = (Pf + Pc)/2 − Pp − (πw − πp)
    = mean_feed_pressure − permeate_pressure − osmotic_differential_at_wall

with πw = β · π_mean(Cf,Cc) (osmotic pressure at membrane wall, corrected for polarization).

Source: ASTM D4516-19a §6; DuPont 45-D01591.

1.7 Osmotic Pressure (π)

Rigorous Van't Hoff:

π = i · M · R · T                                # i ≈ 1.8–2.0 for NaCl
                                                 # R = 0.08314 L·bar/(mol·K)
                                                 # T in Kelvin

Engineering shortcut (industry standard at 25 °C):

π [psi] ≈ 0.0085 · TDS [ppm]
π [bar] ≈ 0.000586 · TDS [ppm]

Shortcut accuracy:

• ±3 % for NaCl-dominated brackish (1 000–10 000 ppm)
• ±5 % for seawater (32 000–40 000 ppm) — agrees with Pitzer model up to 70 g/L NaCl
• Diverges > 10 % for sulfate-rich or hardness-dominated brines — use OLI/PHREEQC instead

Seawater rule of thumb: 35 000 ppm → π ≈ 25–28 bar bulk; ≈ 32–35 bar at wall with β = 1.15.

⚠️ A formula returning π ≈ 8 bar for seawater under-estimates by 3–4× — verify constants and unit handling. The correct order of magnitude for seawater is 25–35 bar.

Source: Pitzer comparison (Tandfonline 2019); Stark-Water RO Working Principle Guide; FilmTec 45-D01591.

1.8 Temperature Correction Factor (TCF)

ASTM D4516-19a normalizes flux to a 25 °C reference. General exponential form:

TCF = exp[ Ke · (1/298 − 1/(273 + T)) ]

Membrane-chemistry constants (Hydranautics TSB 107.28 Apr 2025; FilmTec 45-D01616 Rev 10 Feb 2022):

Membrane type	Ke	Regime
FilmTec BW30 / SW30 (T ≥ 25 °C)	3 020	Hot
FilmTec BW30 / SW30 (T < 25 °C)	2 640	Cold (flux drops faster)
Hydranautics CPA / ESPA	2 500–3 480	Element-specific (TSB 107)
Hydranautics SWC seawater	~3 020

Practitioner shortcut: TCF ≈ 1.03 per °C around 25 °C; doubles every ~25 °C rise.

1.9 Normalized Permeate Flow (NPF) — ASTM D4516-19a §7

NPF = Qp_meas · (NDP_std / NDP_actual) · (TCF_std / TCF_actual)

Action thresholds (industry consensus):

• NPF drop 10 % vs baseline → schedule CIP
• NPF drop 15 % → CIP mandatory
• NPF drop 30 % → autopsy / replacement evaluation

⚠️ NPF cannot be computed without a baseline. Code paths declaring NPF as a field but never populating it because calculate_kpis() receives no baseline are silently broken.

1.10 Normalized Salt Passage (NSP) — ASTM D4516-19a §8

NSP = SP_meas · (mean_C_std / mean_C_actual) · (EPF_actual / EPF_std) · (STCF_std / STCF_actual)

where SP = Cp / mean(Cf, Cc) and STCF is the salt-passage temperature factor (different exponent constant: Ks ≈ 2 200).

Action threshold: NSP rise 15 % → integrity check via ASTM D6908 VDT or ASTM D3923 leak test.

1.11 Element / Vessel / Stage / Train Hierarchy

Train (skid)
└── Stage 1                  ┐ array typically 2:1 or 3:2:1
    ├── Pressure Vessel       │
    │   ├── Element 1         │ standard 8"×40" or 4"×40"
    │   ├── Element 2         │ 6–8 elements per vessel
    │   └── …                 │ typical per-vessel Y = 8–15 %
    └── Stage 2 / 3            reuses concentrate as feed

Per-stage recovery rule of thumb:

• Stage 1 (8 elements, single pass): Y₁ ≈ 50 %
• 2-stage train: Ysys = 1 − (1−Y1)·(1−Y2) ≈ 75 %
• 3-stage train: 85–90 % for high-recovery BWRO

Per-element max: Y_element ≤ 18 % (FilmTec) or ≤ 15 % (Hydranautics).

---

§2 — Authoritative Standards Reference

Standard	Title	Edition	When to invoke
ASTM D4516-19a	Standardizing RO Performance Data	2019	Normalize NPF, NSP — any commissioning, surveillance, warranty claim
ASTM D3923	Detecting Leaks in RO and NF Devices	2023 (also 2018)	New-element acceptance; suspected O-ring / glue-line failure
ASTM D3739-19	Calculation of the Langelier Saturation Index for RO	2019	CaCO₃ scaling prediction; valid for concentrate TDS 10–10 000 mg/L
ASTM D4582	Stiff & Davis Stability Index	current	CaCO₃ scaling at TDS > 10 000 mg/L
ASTM D4194-23	Operating Characteristics of RO and NF Devices	2023	Short-term (< 24 h) factory or commissioning test — not for plant design
ASTM D4195	Water Analysis for RO/NF Application	2014 (withdrawn 2023, still authoritative for scope)	Feedwater characterization scope
ASTM D6161-19	Terminology for Membrane Separation	2019	Definitive glossary; cite to resolve term disputes
ASTM D4189-23	Silt Density Index (SDI)	2023	Pretreatment performance benchmark (30 psi, 0.45 µm, 15 min default)
ASTM D6908	Integrity Testing of Water Filtration Membrane Systems	2025 / 2017	VDT for RO/NF; PDT for UF/MF
ISO 16075-1..4	Treated Wastewater Use for Irrigation	2020 / 2021	Reuse projects; -2 defines water-quality classes A–D
WHO GDWQ 4th ed.	Guidelines for Drinking-water Quality (+ 1st & 2nd Addenda)	2022	Health-based limits: As 10 µg/L, B 2 400 µg/L, F 1.5 mg/L, NO₃ 50 mg/L
USP <645>	Water Conductivity	current	Stage 1 limit 1.3 µS/cm @ 25 °C (uncompensated, in-line) for Purified Water
USP <643>	Total Organic Carbon	current	500 ppb limit for PW and WFI; system suitability with sucrose + 1,4-benzoquinone
Ph. Eur. 0008	Purified Water (Aqua purificata)	current	Equivalent to USP PW; conductivity ≤ 4.3 µS/cm @ 20 °C, TOC ≤ 0.5 mg/L
Ph. Eur. 0169	Water for Injection	Effective 1 April 2017 (Suppl. 9.1)	Allows non-distillation WFI via RO + EDI/UF/NF (note: no 2026 enforcement deadline for this monograph)
Ph. Eur. ch. 2.2.44	TOC in Water for Pharmaceutical Use	Effective 1 July 2026	New harmonized USP/Ph.Eur. method; CRS replaces sucrose/1,4-BQ; updates to "Water" terminology
EN 1717:2025	Protection of Potable Water from Backflow	2025	Fluid categories 1–5; air gaps for RO permeate re-entering potable mains
EN 12952-12	Boiler-feed and Boiler-water Quality	current	Tiered limits keyed to drum pressure class
21 CFR Part 11	Electronic Records & Signatures (US FDA)	—	Data integrity for pharma roadmap
EU Annex 11	Computerised Systems (EudraLex Vol. 4)	—	Risk-based validation; ALCOA+
SEMI F63	Ultrapure Water for Semiconductor Processing	2021	≥ 18.2 MΩ·cm, TOC < 1 ppb, SiO₂ < 0.3 ppb

⚠️ ASTM D4195 is withdrawn (2023) but still cited as authoritative for scope — flag this explicitly when referencing.

⚠️ Ph. Eur. 0169 has no "mandatory 2026-07" deadline. The non-distillation WFI revision took effect 1 April 2017. The 2026-07 date belongs to chapter 2.2.44 (TOC harmonization), which is a different normative artifact.

---

§3 — Vendor Design Guides

3.1 DuPont FilmTec

Key documents: 45-D01504 (master Tech Manual); 45-D01580 (System Design); 45-D01588 (4"/midsize); 45-D01695 Rev 14 Feb 2026 (8" Design Guidelines, current); 45-D01591 (Design Equations); 45-D01616 (Plant Performance Normalization).

Family	Use	Test conditions	Salt rejection
SW30HR / SW30HRLE-440i	Seawater	32 000 ppm NaCl, 800 psi, 25 °C, 8 %	99.7–99.8 %
BW30-400 / BW30HR-440i	Brackish	2 000 ppm NaCl, 225 psi, 25 °C, 15 %	99.5 %
LE / XLE / Eco	Low-energy brackish	500–2 000 ppm, 100–150 psi	99.0–99.4 %

3.2 Hydranautics (Nitto)

TSB index (publicly available at membranes.com):

TSB	Topic
100	Foulant identification
105	Storage and preservation
107.28 (Apr 2025)	Foulants & cleaning procedures; TCF constants
108	Chlorination / dechlorination
110	Operating limits & biocides
111	Biofouling control
113	ESPA/CPA/SWC product specs; oxidation
124	Integrity and VDT
207	Standardization (Hydranautics version of D4516)
414	Caustic / acid CIP procedure

Family	Type	Notes
SWC4 / SWC5 / SWC6	Seawater	99.8 % rejection; ~92 % B rejection @ pH 8
CPA3 / CPA5-LD / CPA7	Brackish high rejection	Low-ΔP variants for fouling
ESPA1 / ESPA2 / ESPA4	Energy saving	Low pressure, tap/municipal
PRO-XS / PRO-XR	Industrial	Lifecycle / robustness

3.3 Toray, Suez/Veolia, LANXESS

Vendor	Series	Notes
Toray	TM820V/M (seawater), TMG20D (brackish low-energy), TM720D (tap)	TM820V-400: 99.8 % @ 32 000 ppm, 800 psi
Suez/Veolia	AG / AK / AD / AE; GenGard antiscalant	AG8040F: ~11 000 GPD, 99.5 %
LANXESS	Lewabrane B400 HR / B440 HR / ULP / ASD	B400 HR: 37.9 m³/d, 99.7 % rejection
LG Chem	NanoH2O	Variable operating windows

3.4 Universal vendor envelope (all polyamide TFC)

Parameter	Limit	Damage mode if exceeded
Max pressure SWRO	83 bar (1 200 psi)	Compaction; glue-line failure
Max pressure BWRO	41 bar (600 psi)	Same
Max ΔP per element	1 bar (15 psi)	Telescoping
Max ΔP per vessel	3.5 bar (50 psi)	Same
Max temperature	45 °C continuous; 35 °C above pH 10	Compaction, hydrolysis
pH range continuous	2–11	Hydrolysis outside
pH range CIP	1–13 (short-term)
Free chlorine	< 0.1 ppm (effectively zero)	Oxidative attack
Other oxidants (O₃, MnO₄⁻, peroxide)	Not tolerated	Same
Max SDI₁₅ feed	5 (3 preferred)	Colloidal fouling
Max turbidity feed	1 NTU

---

§4 — Water Chemistry Essentials

4.1 Conductivity / TDS quick reference (25 °C)

Water type	TDS (mg/L)	Conductivity (µS/cm)
Seawater (open ocean)	32 000–38 000	50 000–58 000
Mediterranean / Red Sea	38 000–43 000	58 000–65 000
High brackish	5 000–15 000	7 000–22 000
Low brackish / well	1 000–5 000	1 500–7 500
Tap (municipal)	100–500	150–750
1st-pass RO permeate (SW feed)	200–500	300–800
1st-pass RO permeate (BW feed)	10–50	15–80
2nd-pass RO permeate	1–5	1.5–8
Mixed-bed DI / EDI product	< 0.1	< 0.1
USP PW limit (Stage 1)	—	≤ 1.3
18.2 MΩ·cm UPW	< 0.06	0.055 (theoretical limit)

Conversion rule (NaCl-dominated): TDS [ppm] ≈ 0.64 × κ [µS/cm] for brackish; 0.55–0.70 for seawater.

4.2 Typical seawater ion composition (mg/L)

Ion	Atlantic	Mediterranean	Red Sea
Na⁺	10 800	12 700	13 500
Cl⁻	19 400	22 900	24 100
SO₄²⁻	2 700	3 200	3 400
Mg²⁺	1 290	1 480	1 590
Ca²⁺	410	470	510
K⁺	390	470	500
HCO₃⁻	142	150	165
Br⁻	67	76	80
Sr²⁺	8	9	13
B (total)	4.5	5.2	6.5
TDS	35 200	41 500	44 000

4.3 pH effects on rejection (pKa-driven)

Species	pKa @ 25 °C	Practical impact
Boron (H₃BO₃ ⇌ B(OH)₄⁻)	9.14–9.24	85–92 % @ pH 8 → > 98 % @ pH 10.5. Double-pass with high-pH 2nd pass is the industry standard for SWRO boron removal
Silica (H₄SiO₄ ⇌ H₃SiO₄⁻)	9.84	Higher pH → higher rejection but raises scaling risk
Ammonia (NH₄⁺ ⇌ NH₃)	9.25	Below pKa: 95 % rejection; above pKa: NH₃ passes (DW concern)
CO₂ / HCO₃⁻ / CO₃²⁻	6.35 / 10.33	At pH < 7 dominated by CO₂ which passes freely; dose NaOH after RO to convert to HCO₃⁻ before EDI

4.4 SDI interpretation (ASTM D4189-23)

SDI₁₅	Interpretation	Action
< 1	Excellent	Years between fouling events
1–3	Acceptable	Months between CIP
3–5	Marginal	Frequent CIP likely; consider UF
> 5	Unacceptable	UF / coagulation / multimedia required

Caveat: SDI is filter-brand-dependent; Modified Fouling Index (MFI) is more rigorous.

4.5 Free chlorine / ORP

• Polyamide TFC tolerance: < 0.1 ppm free Cl₂ continuous
• ORP target after dechlorination: < 200 mV at RO inlet (some specs < 150 mV)
• SBS (sodium bisulfite) dosing: 1.46 mg per mg Cl₂ stoichiometric; practical 1.8–3.0 mg/mg (1.5–2.5× excess)
• Cumulative dose damage tracked in ppm·h — see membrane-troubleshooting §3

4.6 Scaling indices

LSI (Langelier) — for TDS < 10 000 mg/L (ASTM D3739-19):

LSI = pH_actual − pH_s
pH_s = (9.3 + A + B) − (C + D)
  A = f(TDS)
  B = f(T)
  C = f(Ca²⁺ hardness)
  D = f(alkalinity)

LSI > 0 → CaCO₃ scaling tendency. Target: LSI(concentrate) < 0 without antiscalant; < +1.8 with effective inhibitor; up to +2.5 with strong dosing.

S&DSI (Stiff & Davis) — for TDS > 10 000 mg/L (ASTM D4582):

S&DSI = pH − pK2 + pKs − p[Ca²⁺] − p[HCO₃⁻]

Same interpretation as LSI; targets typically < +1.0 with antiscalant.

⚠️ Saturation indices must be computed at the concentrate (last element), not feed — the concentrate is where supersaturation actually occurs.

---

§5 — EDI Quick Reference

5.1 EDI feed envelope

Parameter	Target	Hard limit
Conductivity / FCE	< 30 µS/cm preferred	< 40 µS/cm
Total hardness (as CaCO₃)	< 1 ppm	< 2 ppm (softener required above)
Total CO₂ (CO₂ + HCO₃⁻ + CO₃²⁻)	< 5 ppm	< 10 ppm (NaOH dosing / degasser)
Silica (SiO₂)	< 0.5 ppm	< 1 ppm
TOC	< 0.5 ppm	< 1 ppm
Fe / Mn	< 0.01 ppm each	< 0.05 ppm
Free chlorine	< 0.02 ppm	(destroys resin)
Temperature	10–40 °C standard; 60 °C HWS modules	5–45 °C
Inlet pressure	≤ 7 bar (100 psi)	mechanical limit

5.2 EDI product targets by application

Application	Conductivity	Resistivity	Standard
Pharma PW	≤ 1.3 µS/cm @ 25 °C	≥ 0.77 MΩ·cm	USP <645> Stage 1
Pharma WFI	≤ 1.3 µS/cm + TOC ≤ 0.5 ppm + endotoxin ≤ 0.25 EU/mL	—	Ph. Eur. 0169 / USP WFI
Power-plant UPW	0.1–1 µS/cm	1–10 MΩ·cm	ASME / EPRI
Semiconductor UPW	< 0.055 µS/cm	18.18 MΩ·cm (theoretical)	SEMI F63

5.3 Feed Conductivity Equivalent (FCE)

The manufacturer-standard load metric for EDI sizing — combines conductivity with the ionic load contributed by weak acids when ionized inside the stack:

FCE [µS/cm] = κ + 2.79 · CO₂[ppm] + 1.94 · SiO₂[ppm]

where:

• κ = measured feed conductivity (µS/cm)
• CO₂ = total carbonate (CO₂ + HCO₃⁻ + CO₃²⁻) as ppm CO₂
• SiO₂ = total silica (reactive + colloidal)

Target: FCE 1–5 µS/cm for two-pass RO + EDI to UPW; FCE ≤ 40 µS/cm is the EDI feed limit (stack-dependent 25–43).

⚠️ Coefficient note: some methodologies use 2.66 for CO₂; 2.79 is the SnowPure/E-Cell convention — pick one and be consistent.

💡 EDI alerts that compare against raw feed_conductivity miss CO₂/SiO₂ load and silently allow off-spec operation. Always compute FCE.

---

§6 — Bilingual IT/EN Glossary

6.1 Process KPIs

EN	IT	Note
Recovery	Recupero (Y)	Fraction or %, never raw flow
Rejection	Reiezione (R)	Three flavors: observed / system / intrinsic
Salt passage (SP)	Passaggio salino	SP = 1 − R
Permeate flux	Flusso del permeato (Jw)	LMH (EU) / GFD (US)
Salt flux	Flusso salino (Js)	Sets Cp at given Jw
Net Driving Pressure (NDP)	Pressione netta motrice	Apply gauge pressures consistently
Concentration factor (CF)	Fattore di concentrazione	1/(1−Y) shortcut
Specific energy consumption (SEC)	Consumo energetico specifico	kWh/m³
Normalized permeate flow (NPF)	Portata permeato normalizzata	ASTM D4516
Normalized salt passage (NSP)	Passaggio salino normalizzato	ASTM D4516
Temperature correction factor (TCF)	Fattore di correzione temperatura	Exponential form, Ke per membrane
Concentration polarization (β)	Polarizzazione di concentrazione	Wall/bulk ratio
Differential pressure (ΔP)	Perdita di carico	Per element / vessel / stage

6.2 Phenomena

EN	IT
Fouling	Sporcamento / fouling
Scaling	Incrostazione
Biofouling	Bioincrostazione
Compaction	Compattazione
Concentration polarization	Polarizzazione di concentrazione
Breakthrough	Sfondamento / breakthrough
Hydrolysis	Idrolisi
Oxidation	Ossidazione
Telescoping	Telescopamento (anglicismo accettato)
Channeling	Channeling (anglicismo)

6.3 Components

EN	IT
Skid	Skid / pacchetto pre-assemblato
Train	Treno (impianto)
Element (membrane element)	Elemento (a membrana)
Pressure vessel (PV)	Recipiente in pressione
Stage	Stadio
Pass	Passaggio
Feed spacer	Spaziatore di feed
Permeate channel / carrier	Canale del permeato
Header / manifold	Collettore
Energy Recovery Device (ERD)	Recuperatore di energia (Pelton / PX / DWEER)
High-pressure pump (HPP)	Pompa di alta pressione
Booster pump	Pompa di rilancio
Antiscalant	Antincrostante / antiscalante
Dechlorinator (SMBS)	Dechlorante / metabisolfito di sodio
Cartridge filter	Filtro a cartuccia

6.4 Operations

EN	IT
CIP (Cleaning In Place)	Lavaggio in posto / CIP
Flushing	Lavaggio / flussaggio
Sanitization	Sanitizzazione
Standby / preservation	Conservazione / messa in standby
Set-point	Set-point / valore di consegna
Trip / shutdown	Arresto di emergenza
Commissioning	Messa in servizio
Performance test	Test di prestazione
Autopsy	Autopsia (membrana)
Ramp-up	Avviamento progressivo (≤ 0.7 bar/s)

6.5 Regulatory

EN	IT
Purified Water (PW)	Acqua purificata
Water For Injection (WFI)	Acqua per preparazioni iniettabili
Highly Purified Water (HPW)	Acqua altamente purificata (Ph. Eur. historical)
Drinking water	Acqua potabile / per consumo umano
Reclaimed water	Acqua riutilizzata / di riuso
Endotoxin	Endotossina (EU/mL; LAL test)
Bioburden	Carica microbica (CFU/mL)
Total Organic Carbon (TOC)	Carbonio organico totale

---

Sources

Primary normative — ASTM D4516-19a, D6161-19, D4189-23, D3739-19, D4582, D3923, D4194-23, D6908; ISO 16075-1..4; USP <645>, <643>; Ph. Eur. 0008, 0169 (Suppl. 9.1 effective 2017-04-01), chapter 2.2.44 (effective 2026-07-01); WHO GDWQ 4th ed. (2022 + addenda); EN 1717:2025; EN 12952-12; 21 CFR Part 11; EU Annex 11; SEMI F63:2021.

Vendor manuals — DuPont FilmTec 45-D01504, 45-D01580, 45-D01588, 45-D01591, 45-D01616, 45-D01695 (Rev 14 Feb 2026); Hydranautics TSB 100, 105, 107.28 (Apr 2025), 108, 110, 111, 113, 124, 207, 414; Toray RO Brochure 2024; LANXESS Lewabrane datasheets; LG Chem NanoH2O.

Reference — Lenntech RO chemistry pages; Stark-Water RO Working Principle; Pitzer vs Van't Hoff comparison (Tandfonline 2019); EMA Q&A on non-distillation WFI; PharmOut on Ph. Eur. 0169 (2017); FDCELL on chapter 2.2.44 (2026-07).