What is Cryptosporidium?

Cryptosporidium is a microscopic parasite whose tough “oocyst” form can survive in water and cause gastrointestinal illness if ingested. It’s notorious for being highly chlorine-resistant at typical household levels, which is why relying on chlorine alone is not considered a robust protection for private wells. Instead, the best practice is a multi-barrier design: pre-filtration for sediment/turbidity, absolute 1-micron filtration (or finer) for cyst removal, and ultraviolet (UV) disinfection to inactivate what gets through.

• Invisible You cannot see, smell, or taste Cryptosporidium.
• Hardy Oocysts withstand environmental stress and moderate chlorination.
• Low infectious dose Even a small exposure can make people sick.

How does Crypto reach a private well?

Routes of entry are typically tied to surface-water intrusion or sanitary defects around the wellhead:

• Runoff after rain or flooding can wash animal or human waste toward poorly sealed wells.
• Shallow or spring-fed wells are more exposed to surface influences.
• Cracked casing, missing sanitary cap, or poor grout allow direct entry.
• Nearby septic systems, livestock, wildlife increase risk.

Good to know: Water can look crystal-clear and still carry microscopic oocysts. Appearance is not a safety test.

Health risks & symptoms

Illness caused by Cryptosporidium is called cryptosporidiosis. Common symptoms include watery diarrhea, stomach cramps, nausea, and dehydration. Healthy adults often recover within days to a few weeks, but infants, pregnant people, older adults, and anyone who is immunocompromised may be at greater risk for severe or prolonged illness. Because the infectious dose can be low, prevention is far better than reaction.

Should I test, treat, or both?

Ideally, do both. Comprehensive laboratory testing for parasites is specialized and not always practical; many homeowners rely on a risk-based approach and install a multi-barrier system as insurance. At minimum:

• Perform routine well tests (e.g., coliform bacteria, nitrates). If coliform is present, assume vulnerability and act.
• Assess structural risk: depth, age, casing condition, cap integrity, grading around well.
• After heavy rains or floods, flush, disinfect (as appropriate), retest, and treat water before use.

If anyone in the household is immunocompromised, prioritize a robust barrier approach and add a dedicated drinking-water system (e.g., RO + UV or a certified cyst-removal filter) at the kitchen sink.

The multi-barrier plan that works for Cryptosporidium

For larger homes, light commercial, or small ag applications, higher-capacity systems are available:

6,400 GPD Commercial RO

And if you prefer to browse UV models and accessories by brand:

Shop VIQUA Ultraviolet (UV) Systems

Recommended products for parasite-focused well protection

Tip: When comparing, focus on flow rate (GPM), cartridge availability, and lamp replacement intervals. For families with fluctuating demand, size for peak flow so disinfection stays within spec.

Installation, sizing, & maintenance essentials

Correct order of treatment

1. Well → Sediment pre-filter (5–10 µm)
2. Absolute 1-µm (or finer) filter labeled for “cyst” removal/reduction
3. UV chamber (final stage at point of entry)
4. Optional POU RO/UV at kitchen sink for drinking/cooking

Sizing guidelines (quick reference)

• Peak flow (showers + laundry + faucets) should not exceed your UV system’s rated GPM.
• Choose sediment cartridges that maintain pressure at household flows (consider 20" BB housings for lower pressure drop).
• Verify plumbing space for UV chamber, sleeve access, and service clearances.

Maintenance schedule (typical)

• Sediment cartridge: every 6–12 months (or when pressure drop rises).
• Cyst/polishing cartridge: 6–12 months depending on use and water quality.
• UV lamp: replace annually; clean sleeve during lamp change.
• RO filters: per manufacturer (often 6–12 months for pre/post; membranes 2–3 years).

After heavy rain or flooding: Flush plumbing, change clogged pre-filters, and consider a precautionary boil for drinking/cooking until treatment is confirmed and water runs clear through the system.

Quick owner checklists

Extensive Q&A on Cryptosporidium in wells

Does a water softener remove Cryptosporidium?

No. Softeners remove hardness minerals (calcium/magnesium). They’re not designed for microbial removal. Pair your softener with filtration and UV if hardness and parasites are both concerns. See whole-house filter options and UV systems.

Is chlorine enough?

Not reliably against Crypto. The oocyst form is chlorine-resistant at common doses/contact times. A multi-barrier design (sediment + cyst filtration + UV) is the recommended approach.

What pore size do I need?

Look for absolute 1-micron (or finer) filtration specifically rated for “cyst reduction/removal.” Pair it with UV for a best-practice barrier. Start here: Whole-House Filter Systems.

Will boiling water help in a pinch?

Yes for emergencies: bring to a rolling boil (kitchen use). But boiling is not practical for whole-home use, so install permanent protection at point-of-entry and point-of-use.

My water looks clear. Am I safe?

Clarity is not a safety test. Crypto is microscopic and invisible. Use proper filtration/UV and periodic testing.

Where should the UV go in my plumbing?

Last in the treatment train at point-of-entry, after sediment and cyst filtration, so the water is clear before UV exposure. See: UV Water Sterilization System.

How do I size a UV unit?

Match the UV unit’s rated GPM to your peak household flow (e.g., showers + laundry). If in doubt, size up or call us for help. Browse models in our VIQUA UV collection.

How often do I change filters and the UV lamp?

Sediment and cyst cartridges typically 6–12 months; UV lamp annually; clean the quartz sleeve at lamp change. Mark dates on the housings and set calendar reminders.

What if I’m immunocompromised or have infants/elderly at home?

Increase protection: whole-house cyst filtration + UV and a POU RO/UV at the kitchen sink. Consider more frequent testing and cartridge changes. Start with Under-Sink RO and a UV-rated whole-house option.

Can I combine carbon filtration with UV?

Yes. Carbon improves taste/odor and can reduce certain chemicals. Place carbon blocks after sediment and before UV, ensuring pressure and flow meet spec. The PURA 10 GPM UV Triple integrates sediment + carbon + UV.

Do I need reverse osmosis for the whole house?

Not usually. Whole-house RO is complex and costly. For Crypto, the staple is filtration + UV at entry, with RO reserved for the kitchen to improve taste and add a final membrane barrier.

What happens after a flood?

Assume elevated risk. Avoid using water for drinking/cooking until you flush the system, replace clogged pre-filters, verify UV operation, and (ideally) test. Keep spare cartridges on hand.

Can I install these systems myself?

Experienced DIYers can install housings and UV with the right tools, but many homeowners prefer a licensed plumber. We can help you select parts and coordinate install.

What does “absolute” vs “nominal” micron mean?

“Absolute 1-µm” means the filter’s pore rating is a true cutoff (captures essentially all particles ≥ that size). “Nominal 1-µm” can allow a portion to pass. For Crypto, prefer absolute or filters specifically certified for cyst reduction.

We already have a softener and iron filter. Is that enough?

No. Those solve mineral issues (hardness, iron/sulfur). Add a cyst-rated cartridge and UV to address microbes. See VIQUA UV and Whole-House Filtration.

How do I know if my UV is working?

Most units include an indicator or alarm. Replace lamps on schedule even if they still light; UV intensity drops over time. Keep the sleeve clean and monitor flow.

Can I add protection just at the kitchen sink?

Yes. A RO system plus a cyst-rated final stage (or a compact POU UV) gives excellent drinking-water protection. Whole-house UV is still recommended to protect every tap and shower.

Is there a single all-in-one box for everything?

Some packages bundle sediment + carbon + UV. Example: PURA 10 GPM UV Triple. For best results, we still size and stage each part to your home’s flow and water quality.

Putting it all together: your action plan this week

1. Inspect the wellhead (grading, cap, casing condition) and note any sanitary defects.
2. Install/replace sediment pre-filter to protect everything downstream: Big Blue Whole-House.
3. Add a cyst-rated cartridge (absolute 1-µm or better). See: Whole-House Filters.
4. Finish with UV sized to your peak flow: VIQUA UV or UV Water Sterilization.
5. Upgrade drinking water with Under-Sink RO for taste + added barrier.
6. Schedule maintenance (filters 6–12 months; UV lamp annually) and keep spares ready.

Shop Water Softener Plus