{"id":59651,"date":"2025-10-27T14:50:17","date_gmt":"2025-10-27T06:50:17","guid":{"rendered":"https:\/\/stark-water.com\/?p=59651"},"modified":"2025-10-27T14:50:19","modified_gmt":"2025-10-27T06:50:19","slug":"pure-water-system-buyers-guide","status":"publish","type":"post","link":"https:\/\/stark-water.com\/nl\/blog\/pure-water-system-buyers-guide\/","title":{"rendered":"Pure Water System Buyer\u2019s Guide 2025: How to Choose the Right RO\/DI Equipment"},"content":{"rendered":"<p>This engineer-to-engineer guide explains what a&nbsp;<strong>pure water system<\/strong>&nbsp;is, how RO\/DI\/EDI trains fit into modern plants, and how to size, specify, install and maintain systems with confidence. You\u2019ll find decision maps, component questions, a quick sizing worksheet, a cost model, and an RFQ checklist.<\/p>\n\n\n\n<p>Reviewed by Stark Water Process Engineering Team \u2022 Last updated:&nbsp;20 Oct 2025<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">1) What a pure water system is &amp; where it fits<\/h2>\n\n\n\n<p>A&nbsp;<strong>pure water system<\/strong>&nbsp;removes salts, hardness, organics and microbes to meet a defined product-water spec. Common trains:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>RO only<\/strong>\u00a0(polishing elsewhere): general process water, beverage make-up, lab pre-treatment.<\/li>\n\n\n\n<li><strong>RO \u2192 DI (mixed bed)<\/strong>: high quality with regeneration chemicals; robust when CO<sub>2<\/sub>\/silica are controlled.<\/li>\n\n\n\n<li><strong>RO \u2192 EDI<\/strong>: continuous high resistivity without acid\/caustic; needs good RO and interstage conditioning.<\/li>\n\n\n\n<li><strong>RO \u2192 polishing (carbon\/UF\/UV\/0.2 \u03bcm)<\/strong>: low TOC and microbiological risk for bottling &amp; point-of-use.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Toepassing<\/th><th>Typisch doel<\/th><th>Indicative train<\/th><\/tr><\/thead><tbody><tr><td>Boiler make-up<\/td><td>5\u201320 \u03bcS\/cm<\/td><td>Pretreatment \u2192 RO \u2192 (optional) softener\/MB<\/td><\/tr><tr><td>Food &amp; beverage<\/td><td>1\u201310 \u03bcS\/cm; low TOC<\/td><td>Pretreatment \u2192 RO \u2192 carbon\/UV \u2192 final filter<\/td><\/tr><tr><td>Lab\/process<\/td><td>0.055\u20131 \u03bcS\/cm (18\u20131 M\u03a9\u00b7cm)<\/td><td>Pretreatment \u2192 RO \u2192 EDI or MB \u2192 polishing<\/td><\/tr><tr><td>Electronics\/UPW<\/td><td>18 M\u03a9\u00b7cm; low silica\/TOC<\/td><td>Pretreatment \u2192 RO \u2192 EDI \u2192 mixed-bed \u2192 UPW loop<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">2) Pure Water System Quick decision map<\/h2>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Target resistivity\/conductivity<\/strong>: \u22641 \u03bcS\/cm \u2192 add DI\/EDI; \u22651 \u03bcS\/cm \u2192 RO with polishing may be enough.<\/li>\n\n\n\n<li><strong>Chemical policy<\/strong>: no acid\/caustic on site \u2192 choose\u00a0<strong>EDI<\/strong>; otherwise DI mixed bed is viable.<\/li>\n\n\n\n<li><strong>CO<sub>2<\/sub>\u00a0&amp; silica<\/strong>: if high, add\u00a0<em>interstage<\/em>\u00a0pH\/degassing or choose DI mixed bed polishing.<\/li>\n\n\n\n<li><strong>Micro\/TOC risk<\/strong>: add carbon\/UV\/0.2 \u03bcm and hygienic loop design.<\/li>\n<\/ol>\n\n\n\n<figure class=\"wp-block-image size-large\"><img fetchpriority=\"high\" decoding=\"async\" width=\"1024\" height=\"683\" src=\"https:\/\/stark-water.com\/wp-content\/uploads\/2025\/10\/pure-water-system2-1024x683.webp\" alt=\"pure water system2\" class=\"wp-image-59664\" title=\"\" srcset=\"https:\/\/stark-water.com\/wp-content\/uploads\/2025\/10\/pure-water-system2-1024x683.webp 1024w, https:\/\/stark-water.com\/wp-content\/uploads\/2025\/10\/pure-water-system2-300x200.webp 300w, https:\/\/stark-water.com\/wp-content\/uploads\/2025\/10\/pure-water-system2-768x512.webp 768w, https:\/\/stark-water.com\/wp-content\/uploads\/2025\/10\/pure-water-system2-18x12.webp 18w, https:\/\/stark-water.com\/wp-content\/uploads\/2025\/10\/pure-water-system2-600x400.webp 600w, https:\/\/stark-water.com\/wp-content\/uploads\/2025\/10\/pure-water-system2.webp 1536w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">pure water system2<\/figcaption><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">3) Source water drives design<\/h2>\n\n\n\n<p>Test TDS, hardness, alkalinity\/CO<sub>2<\/sub>, iron\/manganese, turbidity\/SDI, chlorine\/oxidants, and bacteria. Results decide pretreatment and RO recovery limits.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Hardness<\/strong>\u00a0\u2192 scale risk \u2192 softener\/antiscalant + recovery limits.<\/li>\n\n\n\n<li><strong>Iron\/Mn<\/strong>\u00a0\u2192 oxidize &amp; filter before RO; pick non-fouling media.<\/li>\n\n\n\n<li><strong>High SDI<\/strong>\u00a0\u2192 multimedia or\u00a0<a href=\"https:\/\/stark-water.com\/nl\/inside-out-ultrafiltration-membrane\/\">UF pretreatment<\/a>.<\/li>\n\n\n\n<li><strong>Free chlorine<\/strong>\u00a0\u2192 activated carbon and\/or SBS dosing to protect polyamide RO.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">4) Key components &amp; vendor questions<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">RO-membranen<\/h3>\n\n\n\n<p>Ask for brand class, array (4040 vs 8040), design flux, recovery and validated replacement cycles. See&nbsp;<a href=\"https:\/\/stark-water.com\/nl\/hoe-kies-je-de-juiste-maat-ro-membraan-4040-vs-8040-uitgelegd\/\">4040 vs 8040<\/a>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">High-pressure pump<\/h3>\n\n\n\n<p>Check duty point, efficiency, NPSH, seals and noise; match to temperature-corrected RO curve.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Voorbehandeling<\/h3>\n\n\n\n<p>MMF for solids, activated carbon for chlorine\/organics, softener or antiscalant for hardness, UF when SDI is unstable.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Instrumentation &amp; controls<\/h3>\n\n\n\n<p>Pressures &amp; \u0394P, flows, temperature, feed\/permeate conductivity, ORP, pH (interstage), tank levels, event logging.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Skid hygiene<\/h3>\n\n\n\n<p>CIP ports, drainable low points, labeled piping and safe chemical access.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">5) Sizing essentials<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Step<\/th><th>Rule of thumb<\/th><th>Opmerkingen<\/th><\/tr><\/thead><tbody><tr><td>Average flow<\/td><td>From process demand (m\u00b3\/h)<\/td><td>Prefer measured data<\/td><\/tr><tr><td>Herstel<\/td><td>60\u201385% typical<\/td><td>Respect scale\/fouling limits<\/td><\/tr><tr><td>Peak factor<\/td><td>1.3\u20131.6\u00d7<\/td><td>Size tank + loop to cover peaks<\/td><\/tr><tr><td>Loop velocity<\/td><td>0.9\u20131.5 m\/s<\/td><td>Micro control via turbulence<\/td><\/tr><tr><td>Final filter<\/td><td>0.2\u20130.45 \u03bcm integrity-testable<\/td><td>Beverage &amp; sensitive tools<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">6) Materials &amp; workmanship<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>SS316\u00a0for sanitary\/high-temp loops;\u00a0SS304\u00a0for frames\/common headers.<\/li>\n\n\n\n<li>uPVC\/PPR\u00a0acceptable on cold non-sanitary runs within rating.<\/li>\n\n\n\n<li>Compatible elastomers (EPDM\/FKM\/PTFE), clean welds, drainability.<\/li>\n<\/ul>\n\n\n\n<p>See&nbsp;<a href=\"https:\/\/stark-water.com\/nl\/product-categorie\/producten-van-roestvrij-staal\/\">stainless-steel tanks &amp; housings<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">7) Installation, training &amp; warranty<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Commissioning with instrument calibration and baseline logs.<\/li>\n\n\n\n<li>Operator training\u2014start\/stop, CIP\/SIP, chemical safety, daily checks.<\/li>\n\n\n\n<li><strong>12-month warranty<\/strong>\u00a0from start-up; optional extensions.<\/li>\n\n\n\n<li>Spares: cartridges, O-rings, SBS\/antiscalant, pump seal kit, membrane end-caps.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">8) Cost of ownership<\/h2>\n\n\n\n<p>Model electricity (pump kWh), chemicals (SBS\/antiscalant\/cleaners), membranes &amp; cartridges, labor and sanitation cadence. Quick checks:&nbsp;<a href=\"https:\/\/stark-water.com\/nl\/waterzuiveringscalculators\/ro-opex-calculator\/\">RO OPEX calculator<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">9) Compliance &amp; documentation<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>P&amp;IDs, wiring diagrams, instrument ranges &amp; alarm setpoints.<\/li>\n\n\n\n<li>FAT\/SAT with acceptance data and baseline logs.<\/li>\n\n\n\n<li>PM schedule and validated CIP\/SIP procedures.<\/li>\n\n\n\n<li>Align claims to\u00a0<a href=\"https:\/\/www.wqa.org\/learn\/learn-resources\" target=\"_blank\" rel=\"noopener\">WQA resources<\/a>\u00a0en\u00a0<a href=\"https:\/\/www.astm.org\/d1193-06r18.html\" target=\"_blank\" rel=\"noopener\">ASTM D1193<\/a>\u00a0when applicable.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">10) RFQ template (copy &amp; paste)<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><th>Company &amp; site<\/th><td>-<\/td><\/tr><tr><th>Average \/ peak demand<\/th><td>\u2014 m\u00b3\/h \/ \u2014 m\u00b3\/h<\/td><\/tr><tr><th>Target quality<\/th><td>\u2014 \u03bcS\/cm (or \u2014 M\u03a9\u00b7cm); silica \u2264 \u2014 mg\/L; TOC \u2264 \u2014 ppb<\/td><\/tr><tr><th>Feed water<\/th><td>TDS \u2014; hardness \u2014 as CaCO\u2083; SDI \u2014; Fe\/Mn \u2014\/\u2014; free Cl\u2082 \u2014; pH \u2014<\/td><\/tr><tr><th>Preferred train<\/th><td>RO \/ RO+DI \/ RO+EDI \/ RO+polish<\/td><\/tr><tr><th>Materialen<\/th><td>SS316 \/ SS304 \/ uPVC \/ PPR; tank &amp; loop spec<\/td><\/tr><tr><th>Utilities<\/th><td>Power \u2014, compressed air \u2014, drain \u2014<\/td><\/tr><tr><th>Besturingselementen<\/th><td>PLC\/HMI brand, remote I\/O, data logging<\/td><\/tr><tr><th>Delivery &amp; services<\/th><td>Delivery date, installation\/commissioning, training, warranty<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><a href=\"https:\/\/stark-water.com\/nl\/request-a-quote\/\">Een offerte aanvragen<\/a>&nbsp;&nbsp;&nbsp;<a href=\"https:\/\/stark-water.com\/nl\/industrial-water-treatment-guides\/\">More Guides<\/a><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">11) FAQs<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">RO vs DI vs EDI\u2014what\u2019s best for my plant?<\/h3>\n\n\n\n<p>RO for bulk desalting; DI for highest resistivity with chemical regeneration; EDI for continuous high resistivity without acid\/caustic when interstage CO\u2082\/silica are controlled.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">How long do RO membranes last?<\/h3>\n\n\n\n<p>Typically 3\u20135 years with stable pretreatment and periodic CIP; see our&nbsp;<a href=\"https:\/\/stark-water.com\/nl\/how-to-preserve-reverse-osmosis-membranes-after-system-shutdown\/\">membrane care guide<\/a>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Stainless vs plastic piping?<\/h3>\n\n\n\n<p>SS316 for sanitary\/high-temp loops; SS304 for frames\/headers; uPVC\/PPR for cold non-sanitary runs as allowed.<\/p>\n\n\n\n<p><strong>Internal links:<\/strong>&nbsp;<a href=\"https:\/\/stark-water.com\/nl\/installation-diagram-of-reverse-osmosis-membrane\/\">RO membraan behuizing diagram<\/a>&nbsp;-&nbsp;<a href=\"https:\/\/stark-water.com\/nl\/product-categorie\/producten-van-roestvrij-staal\/\">Stainless-steel tanks &amp; housings<\/a>&nbsp;-&nbsp;<a href=\"https:\/\/stark-water.com\/nl\/waterzuiveringscalculators\/lsi-calculator\/\">LSI calculator<\/a>&nbsp;-&nbsp;<a href=\"https:\/\/stark-water.com\/nl\/waterzuiveringscalculators\/chloordosering-rekenmachine\/\">Chloordosering calculator<\/a><\/p>\n\n\n\n<p>Technical guidance only\u2014verify with your feed tests and OEM instructions.<\/p>","protected":false},"excerpt":{"rendered":"<p>This engineer-to-engineer guide explains what a&nbsp;pure water system&nbsp;is, how RO\/DI\/EDI trains fit into modern plants, and how to size, specify, [&hellip;]<\/p>","protected":false},"author":1,"featured_media":59660,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center 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